Boronic polymer crosslinking

ABSTRACT

The object of the invention is polymer compositions comprising cross-linked polymer comprising boronic ester functions enabling exchange reactions, as well as free monofunctional boronic esters. The compositions are obtained from the modification of a polymer by a functionalised boronic ester additive. This polymer can be pre-functionalised boronic ester or functionalised on addition of the said additive. In particular, the invention relates to a process enabling the behaviour of a polymer to be modified by addition of a functional additive, enabling a cross-linked network containing exchangeable boronic ester links to be formed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Divisional of co-pending U.S. application Ser. No.15/243,449 filed on Aug. 22, 2016, which claims priority to FrenchApplication No. 1559955 filed on Oct. 19, 2015 and French ApplicationNo. 1557822 filed on Aug. 20, 2015. The entire contents of all of theabove applications are hereby incorporated by reference.

The invention relates to polymer compositions comprising cross-linkedpolymer comprising boronic ester functions enabling exchange reactions,as well as free monofunctional boronic esters.

Two embodiments, for manufacturing said polymer compositions, are hereindisclosed. The invention is directed to the embodiment of the claims.

In an embodiment, these compositions arise from the polymerisation ofprecursor monomers to thermoplastic polymers comprising at least onepending boronic ester group, said pending boronic ester group notcontaining any polymerisable group and cross-linking agent comprising atleast one boronic ester group enabling the formation of a network ofcross-linked polymer containing pending functions and cross-links thatare exchangeable by boronic ester metathesis reactions.

In another embodiment, these compositions are obtained from themodification of a polymer by a functionalised boronic ester additive.This polymer can be pre-functionalised boronic ester or functionalisedon addition of the said additive. In particular, the invention relatesto a process enabling the behaviour of a polymer to be modified byaddition of a functional additive, enabling a cross-linked networkcontaining exchangeable boronic ester links to be formed.

Surprisingly, a new, rapid boronic ester metathesis reaction has beendiscovered that can be carried out at ambient temperature, with orwithout catalyst. Furthermore, the reaction is advantageouslyquantitative.

“Boronic ester” according to the present invention designates compoundscomprising a dioxaborolane or dioxaborinane group.

“Dioxaborolane” according to the present invention designates a group offormula:

“Dioxaborinane” according to the present invention designates a group offormula:

Substituents on the dioxaborolane and dioxaborinane rings according tothe present invention designate the groups bound to the carbon and boronatoms that constitute the dioxaborolane and dioxaborinane rings.

The boronic ester according to the present invention is a dioxaborolaneor dioxaborinane:

where Rx, Rw and Rv are identical or different and each represent ahydrogen atom or a hydrocarbon radical or form together, as a pair, analiphatic or aromatic ring as defined below. Ry is a hydrocarbon radicalas defined below. According to the invention, the group Ry is bound tothe boronic ester function by a covalent bond through a carbon atom.

According to the invention, the metathesis reaction of the boronicesters enables an exchange reaction between the substituents on theboronic ester rings and can be represented as follows:

“Exchange reaction” designates that organic molecules, oligomers,polymers or polymeric networks containing boronic ester functions offormula (EB1) or (EB2) can exchange their substituents by a boronicester metathesis reaction. These substituents can be hydrocarbon groups,oligomer chains or polymer chains. These groups are bound by covalentbonds, before and after the exchange reaction, to at least one carbonatom of the dioxaborolane or dioxaborinane ring and to the boron atom ofthe dioxaborolane or dioxaborinane ring. The substituents bound to theboron atom of the dioxaborolane or dioxaborinane rings are bound by acovalent bond through a carbon atom.

The boronic ester metathesis reaction does not release a molecule ofwater, and does not require the presence of water to take place.Notably, “exchange reaction” designates that the polymers of theinvention can exchange among themselves the substituents of the boronicester functions (EB1) or (EB2) that they carry by a boronic estermetathesis reaction. According to the invention, these functions can bepending or form part of the polymer chain, notably when they form partof a cross-link. Preferably these functions are pending or form part ofa cross-link. In this way, the polymers are capable of exchangingchemical bonds among themselves.

The metathesis reaction can be carried out in the presence or absence ofcatalyst. Preferably the catalyst is stable, easily available,inexpensive and non-toxic.

The metathesis reaction can be carried in solvent(s) or in bulk, i.e. inthe absence of solvents.

These boronic ester metathesis reaction enable polymer compositions tobe obtained that show the properties of thermoset polymers and ofthermoplastic polymers and which can be insoluble and malleable whenhot.

The boronic esters and the 1,2- or 1,3-diols can also exchange theirsubstituents by a transesterification reaction. Nevertheless, due totheir reactivity, the 1,2- and 1,3-diols lead to numerous parasitereactions, such as etherification or esterification reactions, inpolymer materials containing carboxylic acid or ester groups. The 1,2-and 1,3-diols may also react with other functions of interest. Inaddition to the aforementioned carboxylic acid and ester functions,epoxide, isocyanate and anhydride functions and halogenated derivativesmay be mentioned, without this list being exhaustive. Furthermore, theparasite reactions caused by the presence of 1,2- and 1,3-diols inorganic polymer formulations occur increasingly as the polymers aresubjected to higher temperatures, as is often the case during thecross-linking process, during use and/or shaping or during recycling. Inaddition, certain vinyl monomers of interest, such as acrylates ormethacrylates, are poorly stable or unstable under polymerisationconditions when they carry 1,2-diol or 1,3-diol functions. For thisreason, it is often necessary for 1,2- or 1,3-diol functions to beprotected during the polymerisation step and then deprotected once thepolymer has been synthesised. In this way, the presence of pending1,2-diol or 1,3-diol functions on organic polymers can lead to parasitereactions, limit the functional groups that can be incorporated into theformulations and complicate the polymer manufacturing process by addinga post-polymerisation deprotection step. With this in mind, theinventors have developed cross-linked polymer compositions in which thecross-linking reactions and the exchange reactions do not involve1,2-diols or 1,3-diols.

By definition, a thermoset is a polymer that hardens following an inputof energy, in particular on the action of heat. Thermosets aretraditionally divided into two families depending on theglass-transition temperature (Tg) of their polymer matrix. Thermosetswhose matrix has a Tg higher than the working temperature are calledrigid thermosets, while thermosets whose matrix has a Tg lower than theworking temperature are called elastomers. According to the presentinvention, thermoset designates both rigid thermosets and elastomers.Materials manufactured from thermoset polymers have the advantage ofbeing able to be hardened in a way that gives them a high mechanical,thermal and chemical resistance and for this reason they can replacemetals in certain applications. They have the advantage of being lighterthan metals. They can also be used as matrices in composite materials.Traditional thermosets must be manufactured; in particular they must bemoulded and have the appropriate shape for their final use from thestart. No transformation other than machining is possible once they arepolymerised, and even machining is difficult because of their fragility.Supple and hard parts and composites based on thermoset resins cannot betransformed or shaped; nor can they be recycled. Thermoplastics belongto another class of polymeric materials. Thermoplastics can be shaped athigh temperature by moulding or by injection, but have mechanicalproperties and thermal and chemical resistance that are less interestingthan those of thermosets. In addition, the shaping of thermoplastics canoften only be carried out in a very narrow temperature ranges. Whenthermoplastics are heated, they become liquids the fluidity of whichvaries abruptly around the melting/glass-transition temperatures, whichdoes not allow the application of a range of transformation methods thatexist for glass and for metals for example.

The new polymer compositions, comprising cross-linked polymers, cancombine the mechanical properties and insolubility of a thermoset whilebeing used like a thermoplastic. In this way, it is possible to developpolymer compositions that show the mechanical properties andinsolubility of a thermoset but which can be transformed when hot afterhardening. In particular, it is possible to develop materials that canbe heated to temperatures at which they become liquid without sufferingdestruction or degradation of their structure. In addition, forenvironmental reasons, the polymer composition is preferably recyclable.

A process can be developed to enable the modification of polymerbehaviour, notably thermoplastic behaviour, by cross-linking and thecreation of exchangeable links. Advantageously, these modifications canbe made to the polymer during operations to shape the said polymer, forexample extrusion, injection or compression.

It has also been possible to develop a polymerisation process enabling across/linked network with links, comprising pending links, exchangeableby boronic ester metathesis reactions to be prepared from monomers.Advantageously, the invention proposes additives to be used incombination with the monomers usually used to prepare the thermoplasticpolymers considered.

In this way, the object of the invention is to propose polymercompositions that can combine the properties of thermosets andthermoplastics, that can be prepared:

-   -   by mixing a polymer with one or more additives enabling the        formation of a cross-linked polymer composition, preferably a        cross-linked network, containing pending links and cross-links        that are exchangeable by boronic ester metathesis reactions,        without it being necessary to use polymers or additives        containing 1,2-diol functions or 1,3-diol functions in the        cross-linking step. The polymer of the invention may be        boronic-ester functionalised before the addition of the said        additive or the addition of the said additive may enable the        boronic-ester functionalisation of the polymer and the        cross-linking.    -   by polymerisation of monomers and compounds described below,        leading to a cross-linked network containing pending links and        cross-links that are exchangeable by boronic ester metathesis        reactions. Here again, the presence of 1,2-diol functions or        1,3-diol functions is not necessary for cross-linking and        exchange reactions.

Moreover, the object of the invention is a process to modify thebehaviour, for example the rheology, of a polymer by addition of one ormore additives to the composition comprising such a polymer. Thisadditive or these additives is/are boronic-ester functionalised andenable(s) the formation of a composition of cross-linked polymers,preferably a cross-linked network containing exchangeable links, by aboronic ester metathesis reaction. The polymer may be boronic-esterfunctionalised before the addition of the said additive or the additionof the said additive may enable the boronic-ester functionalisation ofthe polymer and the cross-linking.

Another object of the invention is a polymerisation process leading to across-linked network containing pending links and cross-links that areexchangeable by boronic ester metathesis reactions.

To do this, the inventors have conceived and developed compositions thatenable cross-linked polymer compositions, preferably polymer networks,containing exchangeable cross-links and pending functions to beobtained.

The presence of exchangeable pending functions and exchangeablefunctions in the cross-links enables the macroscopic behaviour of thepolymer networks formed to be easily controlled, independently of thedegree of cross-linking. In this way, for a given degree ofcross-linking, a given temperature and a given strain, a polymer networkof the invention will relax stress quicker if it contains moreexchangeable pending functions. Likewise, for a given degree ofcross-linking, a given temperature and a given shear, a network of theinvention will flow more rapidly if it contains more exchangeablepending functions.

The inventors have tried, without success, to prepare methacrylate andstyrene polymer networks containing pending alcohol functions andcross-links containing ester functions with the aim of obtainingthermosetting systems that, while insoluble even at high temperature,can flow and are malleable.

To do this, polymer networks, prepared by radical polymerisation ofmonomers carrying alcohol functions, such as among others 2-hydroxyethylmethacrylate or 4-vinylbenzyl alcohol, and cross-linking agentscontaining ester functions, such as among others ethylene glycoldimethacrylate, 1,4-butanediol dimethacrylate, 1,6-hexanedioldimethacrylate or bisphenol A dimethacrylate, have been prepared in thepresence of various transesterification catalysts, such as among otherszinc acetate, titanium(IV) ethoxide, titanium(IV) isopropoxide,triphenylphosphine or triazabicyclodecene. The various formulationstested did not enable polymer compositions to be prepared that show themechanical properties of a thermoset while still being transformable athigh temperature after hardening without showing degradation of theirstructure or that could be recycled without the notable loss of theirmechanical properties.

The inventors have also tried, without success, to prepare methacrylatepolymer networks containing cross-links incorporating imine functionsfrom monomers or polymers containing pending primary amine functionswith the aim of obtaining thermosetting systems that, while insolubleeven at high temperature, can flow and are malleable.

To do this, methacrylate polymer networks containing cross-linksincorporating imine functions have been prepared by radicalpolymerisation from methyl methacrylate, of monomers carrying primaryamine functions, such as 2-aminoethyl methacrylate, 2-aminoethylmethacrylamide or 4-vinylbenzylamine, and cross-linking agentscontaining imine functions, such as the compound of formula (I) CF1,and/or terephthaldehyde. The various formulations tested did not enablepolymer compositions to be prepared that show the mechanical propertiesof a thermoset while still being transformable at high temperature afterhardening without showing degradation of their structure or that couldbe recycled without the notable loss of their mechanical properties.

Likewise, the inventors have tried, without success, to preparemethacrylate polymer networks containing pending 1,2-diol and/or1,3-diol functions and cross-links containing the boronic esterfunctions (EB1) or (EB2) with the aim of obtaining thermosetting systemsthat, while insoluble even at high temperature, can flow and aremalleable.

To do this, methacrylate polymer networks containing cross-linksincorporating boronic ester functions have been prepared by radicalpolymerisation from methyl methacrylate, of monomers carrying 1,2-diolfunctions, such as 5,6-hexanediol methacrylate, and dimethacrylate ormethacrylate-styrene cross-linking agents containing the boronic esterfunctions (EB1) or (EB2) between the two functions that can bepolymerised by the radical route, i.e. the two methacrylate functions orthe methacrylate function and the styrene function. The variousformulations tested did not enable polymer compositions to be preparedthat show the mechanical properties of a thermoset while still beingtransformable at high temperature after hardening or that could berecycled without the notable loss of their mechanical properties.

Unexpectedly, the inventors were able to successfully prepare polymernetworks containing pending boronic ester functions and cross-linksincorporating boronic esters. In this way, the inventors have been ableto successfully prepare thermosetting systems that, while insoluble evenat high temperature, can flow and are malleable.

It has been possible to prepare polymer compositions that show themechanical properties and insolubility of a thermoset but that aretransformable after hardening at a temperature higher than the glasstransition temperature (Tg) or the melting temperature (Tf) of thepolymer, preferably higher than Tg or Tf+10° C., more preferably higherthan Tg or Tf+20° C., still more preferably higher than Tg or Tf+40° C.,still more preferably higher than Tg or Tf+80° C., if the glasstransition temperature or the melting temperature is lower than 25° C.,without suffering destruction or degradation of the structure, and thatcan be recycled without notable loss of their mechanical properties.

DESCRIPTION OF THE INVENTION

The object of the invention is a composition comprising (a) cross-linkedpolymers containing exchangeable pending links and exchangeablecross-links, by boronic ester metathesis reactions, preferably obtainedby copolymerisation as described below; and (b) free monofunctionalboronic esters, said boronic esters being chosen from among thefollowing dioxaborolane and dioxaborinane rings of formulas (EB1) and(EB2):

-   -   in which    -   Rx, Rw and Rv are identical or different and each represent a        hydrogen atom or a hydrocarbon group or form together, as a        pair, an aliphatic or aromatic ring    -   Ry is a hydrocarbon radical linked to the boron atom of the        dioxaborolane or dioxaborinane ring by a covalent bond through a        carbon atom.

Preferably the compositions contain less than 0.5 mmol of 1,2-diol and1,3-diol functions per gram of polymer after cross-linking.

In a first embodiment, the composition (a) of cross-linked polymers isprepared by copolymerisation of the following compounds:

-   -   (a) Precursor monomers to thermoplastic polymers comprising at        least one pending boronic ester group, said pending boronic        ester group not containing any polymerisable group;    -   (b) Cross-linking agent comprising at least one boronic ester        group enabling the formation of a network of cross-linked        polymer containing pending functions and cross-links that are        exchangeable by boronic ester metathesis reactions;        -   said boronic esters being chosen from among the following            dioxaborolane and dioxaborinane rings of formulas (EB1) and            (EB2):

-   -   -   in which        -   Rx, Rw and Rv are identical or different and each represent            a hydrogen atom or a hydrocarbon group or form together, as            a pair, an aliphatic or aromatic ring

    -   Ry is a hydrocarbon radical linked to the boron atom of the        dioxaborolane or dioxaborinane ring by a covalent bond through a        carbon atom;

    -   (c) possibly monomers that are precursors to thermoplastic        polymers that do not include a boronic ester group of formula        (EB1) or (EB2).

The cross-linking agent is chosen from among:

-   -   a compound of formula (Ia) or (Ib) below:

-   -   in which n, i, k, ki, R₁, R′₁, R″₁, R_(3i), R′_(3i), R″_(3i),        R₅, R″₅, R_(7i), R″_(7i), R₆, each R_(8i), R₂ and R₄, are        defined below. R₂ is linked to the boronic ester function by a        covalent bond through a carbon atom. R₆, each R_(8i) is linked        to the boron atom by a covalent bond through a carbon atom.    -   a monomer (b) boronic ester functional compound, precursor to a        thermoplastic polymer or thermoset, comprising at least one        boronic ester function per monomer and carrying at least one        polymerisable group    -   and their mixtures.

In particular, the monomer (b) is of formula (IIIa), (IIIb1) or (IIIb2)below:

in which R₃₁, R″₃₁, R″₃₁, R₃₅, R″₃₅, R₃₆, R₃₂ and R₃₄, GFP₃, m₃, k areas defined below. R₃₆ is linked to the boronic ester function by acovalent bond through a carbon atom. R₃₆ is linked to the boron atom bya covalent bond through a carbon atom

In particular, monomer (b) has the formula (IVa) or (IVb) below:

in which R₄₁, R″₄₁, R₄₅, R″₄₅, R₄₂, R′₄₂, R₄₆ and R₄₄, GFP₄, GFP′₄ m₄and k are as defined below. R₄₂ is linked to the boronic ester functionby a covalent bond through a carbon atom. R₄₆ is linked to the boronatom by a covalent bond through a carbon atom.

Preferably the monomers (a), (b) and (c) include a single polymerisablegroup and the polymerisation is a radical polymerisation, apolymerisation by coordination or a ring-opening polymerisation or themonomers (a), (b) and (c) include only two polymerisable groups and thepolymerisation is a polyaddition or a polycondensation.

According to the invention, any function that can give rise to twoaddition or condensation reactions by the mode of monomer polymerisationinvolved is equivalent to two polymerisable groups.

In a second embodiment, the object of the invention is a compositioncomprising (a) cross-linked polymers containing exchangeable pendinglinks and exchangeable cross-links, by boronic ester metathesisreactions, obtained by cross-linking of linear or branched polymers; and(b) free monofunctional boronic esters, said boronic esters being chosenfrom among the following dioxaborolane and dioxaborinane rings offormulas (EB1) and (EB2):

-   -   in which    -   Rx, Rw and Rv are identical or different and each represent a        hydrogen atom or a hydrocarbon radical or form together, as a        pair, an aliphatic or aromatic ring.    -   Ry is a hydrocarbon radical linked to the boron atom of the        dioxaborolane or dioxaborinane ring by a covalent bond through a        carbon atom.

The linear or branched polymers preferably contain less than 1 mmol of1,2-diol and/or 1,3-diol functions per gram of polymer beforecross-linking and the compositions preferably contain less than 0.5 mmolof 1,2-diol and/or 1,3-diol functions per gram of polymer aftercross-linking.

Preferably, the polymers, before cross-linking, are linear or branchedpolymers having side-groups carrying:

-   -   boronic ester functional groups of formula (EB1) or (EB2) linked        to the polymer by at least one carbon atom of the dioxaborolane        or dioxaborinane ring; or    -   boronic ester functional groups of formula (EB1) or (EB2) linked        to the polymer by the boron atom of the dioxaborolane or        dioxaborinane ring.

In an embodiment of the invention, the composition results from themixture, in the molten state or in solution:

-   -   Of at least one linear or branched polymer P1 with side-groups        carrying:        -   boronic ester functional groups of formula (EB1) or (EB2)            linked to the polymer by at least one carbon atom of the            dioxaborolane or dioxaborinane ring; or        -   boronic ester functional groups of formula (EB1) or (EB2)            linked to the polymer by the boron atom of the dioxaborolane            or dioxaborinane ring.    -   Of at least one additive carrying at least two boronic ester        groups of formula (EB1) or (EB2) that are capable of reacting        with the side groups of the polymer P1 to form a cross-linked        polymer composition, preferably a cross-linked network, with        pending links and cross-links that are exchangeable by boronic        ester metathesis reactions.

The additive or cross-linking agent is preferably a compound of formula(Ia) or (Ib) as described above and below.

The additive can also be a linear or branched polymer P2 carrying

-   -   boronic ester functional groups of formula (EB1) or (EB2) linked        to the polymer by at least one carbon atom of the dioxaborolane        or dioxaborinane ring; or    -   boronic ester functional groups of formula (EB1) or (EB2) linked        to the polymer by the boron atom of the dioxaborolane or        dioxaborinane ring.

In an embodiment of the invention, the composition results from themixture, in the molten state or in solution:

-   -   Of at least one linear or branched polymer P1′ containing        functions enabling grafting,    -   A combination of molecules of which the molecules comprise at        one end a functional group enabling covalent binding of the        molecule to the polymer P1′ and at the other end a functional        group chosen from among a boronic ester function of formula        (EB1) or (EB2) linked to the rest of the molecule by at least        one carbon atom of the dioxaborolane or dioxaborinane ring, a        boronic ester function of formula (EB1) or (EB2) linked to the        rest of the molecule by its boron atom, and/or molecules        comprising at two of their extremities functional groups        enabling covalent binding of the molecule to the polymer P1′ and        between these two extremities a boronic ester function of        formula (EB1) or (EB2), the combination enabling grafting and        the creation of pending links and cross-links exchangeable by        boronic ester metathesis reactions.

The linear or branched polymer, preferably P1, P1′ or P2, is preferablya polymer chosen from among vinyl polymers, polyolefins, polyamides,polysiloxanes or silicones, and polysaccharides.

Another object of the invention is a process for preparing across-linked polymer composition, said process comprising the followingsteps:

-   -   Choosing a linear or branched polymer P1 with side-groups        carrying:        -   boronic ester functional groups of formula (EB1) or (EB2)            linked to the polymer by at least one carbon atom of the            dioxaborolane or dioxaborinane ring; or        -   boronic ester functional groups of formula (EB1) or (EB2)            linked to the polymer by the boron atom of the dioxaborolane            or dioxaborinane ring.    -   Choosing at least one additive carrying at least two boronic        ester groups of formula (EB1) or (EB2) that are capable of        reacting with the side groups of the polymer P1 to form a        cross-linked polymer composition, preferably a cross-linked        network, containing links and cross-links that are exchangeable        by boronic ester metathesis reactions.    -   Mixing, in the molten state or in solution, said polymer P1 and        said additive to obtain the said composition.

Another object of the invention is a process for preparing across-linked polymer composition, said process comprising the followingsteps:

-   -   Choosing a linear or branched polymer P1′ containing functions        enabling grafting;    -   Choosing a combination of molecules of which the molecules        comprise at one end a functional group enabling covalent binding        of the molecule to the polymer P1′ and at the other end a        functional group chosen from among a boronic ester function of        formula (EB1) or (EB2) linked to the rest of the molecule by at        least one carbon atom of the dioxaborolane or dioxaborinane        ring, a boronic ester function of formula (EB1) or (EB2) linked        to the rest of the molecule by its boron atom, and/or molecules        comprising at two of their extremities functional groups        enabling covalent binding of the molecule to the polymer P1′ and        between these two extremities a boronic ester function of        formula (EB1) or (EB2), the combination enabling grafting and        the creation of pending links and cross-links that are        exchangeable by boronic ester metathesis reactions.    -   Mixing, in the molten state or in solution, said polymer P1′ and        said combination.

Another object of the invention is a material obtained from thecomposition according to the invention. Another object of the inventionis a formulation comprising a composition according to the invention.

Another object of the invention is the use of an additive such asdefined in the invention, or the combination such as defined in theinvention, in the presence of a linear or branched polymer P1 or P1′ forthe formation of a composition comprising cross-linked polymers,preferably a cross-linked network, containing pending links andcross-links that are exchangeable by boronic ester metathesis reactionsand free monofunctional boronic esters of formula (EB1) or (EB2).

Another object of the invention are combinations to cross-link linear orbranched polymers, said combinations being chosen from among thecombinations comprising:

-   -   A+B;    -   A and/or B+C;    -   A+compound of formula (Ia); or    -   B+compound of formula (Ib).    -   A, B and C corresponding to the following formulas:

-   -   where    -   G₁, G₂, G₃ and G₄ each represent, independently from one        another, a functional group enabling the covalent binding of the        molecules to the polymer chain to be functionalised;    -   Rx, R″x, and Ry, R′y, R″y are hydrocarbon groups;    -   R′v, R′w and R′x, identical or different, each represent a        hydrogen atom, a hydrocarbon radical, or form together, as a        pair, an aliphatic or aromatic ring;    -   Rv and Rw, respectively R″v and R″w, identical or different,        represent a hydrogen atom, a hydrocarbon radical or form an        aliphatic or aromatic ring together, or with Rx, respectively or        with R″x;    -   Ry, R′y, R″y are linked to the boron through a carbon atom.

Another object of the invention is the use of a combination according tothe invention, in the presence of a linear or branched polymer P1 or P1′for the formation of a composition comprising cross-linked polymers,preferably a cross-linked network, containing pending links andcross-links that are exchangeable by boronic ester metathesis reactionsand free monofunctional boronic esters of formula (EB1) or (EB2), inparticular for modifying the rheology of a composition, such as an oilor a paint, comprising the said polymer P1 or P1′ by addition of thecombination according to the invention to the composition; the rheologyis modified by choosing the concentration of the said combination.

Definitions

Definition of Polymer, Linear Polymer, Branched Polymer:

A polymer comprises a set of polymer chains of different moleculardimensions, notably of different molar masses. The polymer chains aremade up from the covalent assembly of a large number of repetitive unitscalled monomer units. The polymer chains so defined have moleculardimensions (characterised by their molar mass) very much larger thanthose of simple molecules, and are made up from the covalent assembly ofmore than 5 monomer units, preferably of more than 20 monomer units,still more preferably of more than 50 monomer units.

Polymer chains comprising a single type of monomer unit are calledhomopolymers. Polymer chains comprising several types of monomer unitare called copolymers. According to this invention, polymer and polymerchain designate both homopolymers and copolymers.

The monomer units constituting the polymer chain may be linked to avariable number of other monomer units. The number of other monomerunits to which a monomer unit is linked is called valence. A monomerunit that is linked to a single other monomer unit has a valence of 1and corresponds to an extremity of the polymer chain. A monomer unitthat is linked to two other monomer units has a valence of 2 andcorresponds to a linear sequence of a polymer chain. A monomer unit thatis linked to more than two other monomer units has a valence greaterthan 2 and corresponds to a branching point. A polymer chain with twoextremities is a linear polymer chain. A linear polymer chain istherefore composed of monomer units with a valence of 2 and two unitswith a valence of 1. A polymer chain that has more than two extremitiesand whose molar mass has a finite value is a branched polymer chain. Abranched polymer chain is therefore composed of monomer units with avalence of 2, monomer with a valence greater than 2, and more than twomonomer units with a valence of 1.

According to this invention, polymer and polymer chain designate bothlinear polymer chains and branched polymer chains.

Definition of Boronic Ester:

“Boronic ester” according to the present invention designates compoundscomprising a dioxaborolane or dioxaborinane group, as defined in theintroduction.

Definition of 1,2-Diol and 1,3-Diol:

“1,2-Diol” according to the present invention designates a compound,whether it be a free organic molecule, an oligomer, a polymer, or apolymer network, containing two hydroxyl (—OH) groups on adjacent, orvicinal, carbon atoms. Non-limiting examples include ethane-1,2-diol orethylene glycol (HO—(CH₂)₂—OH), or propane-1,2-diol (or propyleneglycol, HO—CH₂—CH(OH)—CH₃).

“1,3-Diol” according to the present invention designates a compound,whether it be a free organic molecule, an oligomer, a polymer, or apolymer network, containing two hydroxyl (—OH) groups on carbon atomsseparated by one atom. Non-limiting examples include propane-1,3-diol(HO—(CH₂)₃—OH) or butane-1,3-diol (HO—(CH₂)₂—CH(OH)—CH₃).

Definition of Pending Function:

A boronic ester function (EB1) or (EB2) is pending if it is linked by acovalent bond to a monomer unit with a valence greater than 1 by one andonly one of its hydrocarbon substituents Rx or Ry (see followingdefinition) or by its substituents {Rx, Rw} or {Rx, Rv} if these formtogether an aliphatic or aromatic ring. In other words, a function ispending if it is linked by a covalent bond to a polymer chain by one andonly one of its hydrocarbon substituents Rx or Ry (see followingdefinition) or by its substituents {Rx, Rw} or {Rx, Rv} if these formtogether an aliphatic or aromatic ring and if it does not constitute anextremity of the polymer chain.

A boronic ester function (EB1) or (EB2) is terminal, or constitutes achain extremity, if it is linked by a covalent bond to a monomer unitwith a valence equal to 1 by one and only one of its hydrocarbonsubstituents Rx or Ry (see following definition) or by its substituents{Rx, Rw} or {Rx, Rv} if these form together an aliphatic or aromaticring.

A boronic ester function (EB1) or (EB2) forms part of a cross-link if itis linked by its hydrocarbon substituent Rx through a covalent bond to amonomer unit covalently connected to at least two other monomer unitsnot comprising the said boronic ester function, and if it is linked byits hydrocarbon substituent Ry through a covalent bond to a monomer unitcovalently connected to at least two other monomer units not comprisingthe said boronic ester function.

When it substituents {Rx, Rw} or {Rx, Rv} together form an aliphatic oraromatic ring, a boronic ester function (EB1) or (EB2) can also formpart of a cross-link if it is linked, by its substituents {Rx, Rw} or{Rx, Rv}, to a monomer unit covalently connected to at least two othermonomer units not comprising the said boronic ester function, and if itis linked by its hydrocarbon substituents Ry through a covalent bond toa monomer unit covalently connected to at least two other monomer unitsnot comprising the said boronic ester function.

In this way, the term “pending group” according to the present inventiondesignates a side-group of the polymer chain. “Side-group” according tothe present invention designates a substituent that is not an oligomeror a polymer. A side-group is not integrated into the main chain of thepolymer. “Pending boronic ester group” according to the presentinvention designates a side group comprising a dioxaborolane function ora dioxaborinane function. In this way, when a boronic ester of formula(EB1) or (EB2) is pending, one of its two substituents Rx or Ry is notlinked to a polymer chain except through its own boronic ester function.Furthermore, when a boronic ester of formula (EB1) or (EB2) is pending,it substituents Rv and Rw are not linked to a polymer chain, exceptthrough the said boronic ester function, unless one of them forms analiphatic or aromatic ring with the Rx substituent on another carbonatom of the dioxaborolane or dioxaborinane ring and that the said Rxsubstituent is linked to a polymer chain. The boronic ester of formula(EB1) or (EB2) may be linked with the side group by the boron atom ofits dioxaborolane or dioxaborinane ring, by one of the carbon atoms ofits dioxaborolane or dioxaborinane ring, or by two or three of thecarbon atoms of its dioxaborolane or dioxaborinane ring if thesetogether form an aliphatic or aromatic ring.

When the expression “pending boronic ester function” is used to qualifya monomer, it designates, according to the invention, that afterpolymerisation of the said monomer, the said boronic ester function willbe pending or will form part of a cross-link. In this way, theexpression “monomer having a pending boronic ester function” designatesthat after polymerisation of the said monomer, the boronic esterfunction considered will not form part of the main chain of the polymerobtained.

Definition of a Free Molecule:

According to this invention, a molecule is said to be “free” if it isnot linked by a covalent bond to a polymer of the composition.

According to this invention, a “free monofunctional boronic ester” is afree molecule containing one and only one boronic ester function (EB1)or (EB2). A “free monofunctional boronic ester” may or may not containone or more other functions insofar as these are not boronic esterfunctions (comprising boronic esters other than those of formula (EB1)or (EB2)), boronic acid, 1,2-diols or 1,3-diols.

Definition of Cross-Linking:

Cross-linking, or polymer chain cross-linking, consists of creatingcovalent chemical bonds between polymer chains that initially are notlinked to other by covalent bonds. Cross-linking is accompanied by anincrease in connectivity, through covalent bonds, between the variouschains that make up the polymer. The cross-linking of linear or branchedpolymer chains is accompanied by an increase in the molecular dimensionsof the chains, notably of the molar masses, and can lead to a network ofcross-linked polymers being obtained. The cross-linking of a network ofcross-linked polymers is accompanied by an increase in the mass fractioninsoluble in good non-reactive solvents according to the definitiongiven below.

According to the invention, cross-linking is the result, among othercauses, of metathesis reactions between the boronic ester functions(EB1) or (EB2) on the pending groups of the polymers and/or on thepending groups in the polymers and on compounds of formula (Ia) or (Ib),defined below. Preferably, cross-linking is the result of metathesisreactions between the boronic ester functions on the pending groups ofthe polymers and/or on the pending groups in the polymers and oncompounds of formula (Ia) or (Ib). In this way, for every cross-linkingreaction by metathesis reaction between boronic ester functions, oneequivalent of free monofunctional boronic ester is generated, asillustrated in FIG. 3 in the case of cross-linking by a metathesisreaction of linear polymers functionalised by complementary pendingdioxaborolane functions. Preferably, cross-linking results exclusivelyfrom metathesis reactions between the boronic ester functions on thepending groups of the polymers and/or on the pending groups in thepolymers and on compounds of formula (Ia) or (Ib).

“Cross-linked network” according to the present invention designates anetwork of cross-linked polymers.

“Network of cross-linked polymers” according to the present inventiondesignates a set of polymer and/or oligomer chains linked to each otherby covalent bonds that, when immersed at a mass fraction of 1/10 in agood non-reactive solvents for the polymer and/or oligomer chains thatit is constituted of shows an insoluble mass fraction greater than 0.1%,preferably greater than 0.5%, 1%, 2%, 5%, 10%, 20%, 30%, 40%, 50% and70%, after 48 hours of immersion at atmospheric pressure and at atemperature between the melting temperature and the boiling temperatureof the solvent. A good non-reactive solvent is a good solvent that willnot degrade the polymer chains, that will not degrade or react with,notably by transesterification reactions, the boronic ester functionsand that will not participate in boronic ester metathesis reactions. Theinsolubility can be assessed by the naked eye or by passing theformulation through a filter with a porosity of 0.2 micrometre,preferably of 0.4 micrometre, still more preferably of 1 micrometre.

Cross-linking is accompanied by the creation of cross-links linking atleast two polymer chains to each other. These cross-links preferablycontain boronic ester functions. In this way, after cross-linking, thecomposition includes boronic ester functions in the cross-links andpreferably polymers comprising pending boronic ester functions.

Definition of the Glass Transition:

The glass transition temperature, Tg, is defined as the temperature atwhich the value of the damping factor, or loss factor, tan 8 is at amaximum by dynamic mechanical analysis at 1 Hz. The damping factor, orloss factor, tan 8, is defined as the ratio of the loss modulus E″ tothe conservation modulus E′ (Mechanical Properties of Solid Polymers,Author(s): I. M. Ward, J. Sweeney; Editor: Wiley-Blackwell; Edition: 3rdEdition; Print ISBN: 9781444319507; DOI: 10.1002/9781119967125).

Definition of Polymer Composition:

A polymer composition is defined as a homogenous or non-homogenousmixture of linear or branched polymers, which may be linked bycross-links, containing pending links and cross-links that areexchangeable by boronic ester metathesis reactions, potentially withvarious charges, additives or solvents, as defined below.

In this way, “polymer composition” designates both solid formulationsthat contain little or no solvent(s) and liquid formulations containinga higher mass fraction of solvent(s).

In this way, “formulation” designates both solid formulations and liquidformulations.

According to the invention, a solid formulation contains less than 30%by mass of solvent(s), preferably less than 25% by mass of solvent(s),more preferably less than 20% by mass of solvent(s), still morepreferably less than 15% by mass of solvent(s), still more preferablyless than 5% by mass of solvent(s), still more preferably less than 2.5%by mass of solvent(s), still more preferably less than 1% by mass ofsolvent(s) and still more preferably less than 0.5% by mass ofsolvent(s).

According to the invention, a solid formulation is a material.

According to the invention, a liquid formulation contains more than 30%by mass of solvent(s), preferably more than 50% by mass of solvent(s),more preferably more than 60% by mass of solvent(s), still morepreferably more than 70% by mass of solvent(s) and still more preferablymore than 75% by mass of solvent(s).

According to the invention, a liquid formulation may be a material.

A solvent is defined as a molecule, or a mixture of molecules, that isliquid at ambient temperature and that has the property, at ambienttemperature, of dissolving and/or diluting other substances withoutmodifying them chemically and without being modified itself. Amongsolvents, a distinction is made between good solvents, which present theproperty of dissolving substances at room temperature without modifyingthem chemically and without being modified themselves, and poorsolvents, which present the property of diluting substances at ambienttemperature without dissolving them, modifying them chemically andwithout being modified themselves.

A solvent can therefore be a good solvent for one compound and a poorsolvent for another compound.

Non-limiting examples of solvents include ethyl acetate, butyl acetate,acetone, acetonitrile, benzyl alcohol, acetic anhydride, anisole,benzene, butanol, butanone, chlorobenzene, chloroform, cyclohexane,dichloroethane, dichloromethane, dimethylformamide, dimethyl sulfoxide,dioxane, water, ethanol, glycol ether, diethyl ether, ethylene glycol,heptane, hexane, mineral oils, natural oils, synthetic oils,hydrocarbons, methanol, pentane, propanol, propoxypropane, pyridine,tetrachloroethane, tetrachloromethane, tetrahydrofuran, toluene,trichlorobenzene, xylene, and their mixtures.

Definition of Radicals:

A “hydrocarbon” group according to the present invention is a groupconsisting of atoms of carbon and hydrogen. This group may also includeheteroatoms and/or be substituted by halogens. The hydrocarbon grouppreferably includes 1-50, more preferably 1-18, still more preferably1-12 carbon atoms.

“Heteroatom” according to present invention designates atoms of sulfur,nitrogen, oxygen, boron, phosphorus or silicon.

“Halogen” according to present invention designates atoms of fluorine,chlorine, bromine or iodine.

Hydrocarbon groups may be aliphatic or aromatic.

“Aliphatic” according to the present invention designates an “alkyl”,“alkenyl”, “alkanediyl”, “alkenediyl” or “cycloalkyl” group. The valenceof the group will be determined case-by-case.

An aliphatic group may include heteroatoms. In particular, it mayinclude ester, amide, ether, thioether, secondary or tertiary amine,carbonate, urethane, carbamide or anhydride functions. If applicable,the aliphatic group may be substituted notably by a halogen, an -Rz,—OH, —NH2, —NHRz, —NRzR′z, —C(O)—H, —C(O)—Rz, —C(O)—OH, —C(O)—NRzR′z,—C(O)—O-Rz, —O—C(O)-Rz, —O—C(O)—O-Rz, —O—C(O)—N(H)-Rz, —N(H)—C(O)—O-Rz,—O-Rz, —SH, —S-Rz, —S—S-Rz, —C(O)—N(H)-Rz, —N(H)—C(O)-Rz group with Rz,R′z, identical or different, representing a C₁-C₅₀ alkyl radical, or bya functional group chosen from among the functional groups that arepolymerisable by radical polymerisation and the boronic ester functionsof formula (EB1) or (EB2).

An “alkyl” group according to the present invention designates asaturated or unsaturated, linear or branched hydrocarbon chain,preferably comprising 1-50 carbon atoms, more preferably 1-18 carbonatoms, still more preferably 1-12 carbon atoms, and which can includeone or more heteroatoms. In this way, according to the invention,ignoring the strict sense of the term, “alkyl” also includes:

-   -   “alkenyls”, that is hydrocarbon chains comprising at least one        double bond;    -   “heteroalkyls”, that is alkyl groups as defined above comprising        at least one heteroatom.

An “alkanediyl” group according to the present invention designates adivalent, saturated or unsaturated, linear or branched hydrocarbonchain, preferably comprising 1-50 carbon atoms, more preferably 1-18carbon atoms, still more preferably 1-12 carbon atoms, and which caninclude one or more heteroatoms. In this way, according to theinvention, ignoring the strict sense of the term, “alkanediyl” alsoincludes “alkenediyls”, that is hydrocarbon chains comprising at leastone double bond, for example a vinylene (ethenylene) group or apropenylene group, and “heteroalkanediyls”, that is alkanediyl groups asdefined above comprising at least one heteroatom.

A “cycloalkyl” group according to the present invention designates acyclical alkyl chain, which may be saturated or partially unsaturatedbut not aromatic, preferably comprising 3-10 carbon atoms in the ring.The alkyl chain may include one or more heteroatoms; in this case itwill be specifically called “heterocycloalkyl”. The group may includemore than one ring, and in this way includes fused, linked or spirorings. Examples include cyclopropyl, cyclopentyl, cyclohexyl,cycloheptyl, pyrrolidinyl, piperidinyl, piperazinyl or morpholinylgroups. If applicable, the cycloalkyl group may be substituted notablyby a halogen, an -Rz, —OH, —NH2, -NHRz, —NRzR′z, —C(O)—H, —C(O)—Rz,—C(O)—OH, —C(O)—NRzR′z, —C(O)—O-Rz, —O—C(O)-Rz, —O—C(O)—O-Rz,—O—C(O)—N(H)-Rz, —N(H)—C(O)—O-Rz, —O-Rz, —SH, —S-Rz, —S—S-Rz,—C(O)—N(H)-Rz, —N(H)—C(O)-Rz group with Rz, R′z, identical or different,representing a C₁-C₅₀ alkyl radical, or by a functional group chosenfrom among the functional groups that are polymerisable by radicalpolymerisation and the boronic ester functions of formula (EB1) or(EB2). If applicable, the cycloalkyl group maybe divalent; in this caseit is preferably called a “cycloaliphatic” radical.

“Aromatic” according to the present invention designates a monovalent ormultivalent group comprising an aromatic hydrocarbon group. The valenceof the group will be determined case-by-case.

The aromatic group may include heteroatoms; in this case it is called a“heteroaromatic” radical. In particular, it may include ester, amide,ether, thioether, secondary or tertiary amine, carbonate, urethane,carbamide or anhydride functions. An aromatic group may include one ormore rings that are fused or covalently linked. If applicable, thearomatic group may be substituted notably by a halogen, an -Rz, —OH,—NH2, —NHRz, —NRzR′z, —C(O)—H, —C(O)—Rz, —C(O)—OH, —C(O)—NRzR′z,—C(O)—O-Rz, —O—C(O)-Rz, —O—C(O)—O-Rz, —O—C(O)—N(H)-Rz, —N(H)—C(O)—O-Rz,—O-Rz, —SH, —S-Rz, —S—S-Rz, —C(O)—N(H)-Rz, —N(H)—C(O)-Rz group with Rz,R′z, identical or different, representing a C₁-C₅₀ alkyl radical, or bya functional group chosen from among the functional groups that arepolymerisable by radical polymerisation and the boronic ester functionsof formula (EB1) or (EB2).

The term “aromatic” includes “arylaromatic” groups, that is a groupcomprising at least one aromatic group and at least one aliphatic group,as defined. The aliphatic group may be linked to one part of themolecule and the aromatic group to another part of the molecule. Thegroup may include two aromatic groups, each linked to a part of themolecule and linked between them by an aliphatic chain.

“Aryl” according to the present invention designates an aromatichydrocarbon group. The term “aryl” includes aralkyl and alkyl-arylgroups. The aromatic hydrocarbon group may be substituted once or morethan once notably by a halogen, an -Rz, —OH, —NH2, -NHRz, —NRzR′z,—C(O)—H, —C(O)—Rz, —C(O)—OH, —C(O)—NRzR′z, —C(O)—O-Rz, —O—C(O)-Rz,—O—C(O)—O-Rz, —O—C(O)—N(H)-Rz, —N(H)—C(O)—O-Rz, —O-Rz, —SH, —S-Rz,—S—S-Rz, —C(O)—N(H)-Rz, —N(H)—C(O)-Rz group with Rz, R′z, identical ordifferent, representing a C₁-C₅₀ alkyl radical, or by a functional groupchosen from among the functional groups that are polymerisable byradical polymerisation and the boronic ester functions of formula (EB1)or (EB2).

“Alkyl-aryl” according to the present invention designates an alkylgroup, as defined above, linked to the rest of the molecule through anaromatic group, as defined above.

“Aralkyl” according to the present invention designates an aryl group,as defined above, linked to the rest of the molecule through analiphatic group, as defined above.

“Heteroaryl” according to the present invention designates an aryl groupin which at least one of the atoms of the aromatic ring is a heteroatom.“Heteroalkyl-aryl” according to the present invention designates analkyl-aryl group, as defined, substituted by at least one heteroatom.“Heteroaralkyl” according to the present invention designates an aralkylgroup, as defined, substituted by at least one heteroatom.

The boronic ester functions present in the polymers and compounds willhereinafter be referred to generically by the formulas (EB1) and (EB2).It is to be understood that the definition of the substituents of theboronic esters may vary independently from one compound to another.

DESCRIPTION OF THE DRAWINGS

FIG. 1. Representation of the molecules that may be used for thefunctionalisation and one-step cross-linking of the polymers.

FIG. 2. Schematic representation of the functionalisation of linearpolymers by molecule A in the case of a dioxaborolane cyclic boronicester (left), or molecule B in the case of a dioxaborolane cyclicboronic ester (right), through the creation of covalent bonds betweenmolecule A, or B, and the polymer chains. The functions enabling thegrafting of molecules A in the case of a dioxaborolane cyclic boronicester (left), or molecule B in the case of a dioxaborolane cyclicboronic ester (right), may form part of the main chain (above) orside/pending groups (below) of the main polymer chain to befunctionalised.

FIG. 3. Schematic representation of cross-linking by a metathesisreaction of linear polymers functionalised by complementary pendingdioxaborolane functions.

FIG. 4. Evolution of the molar percentage (ordinate; without unit) ofthe different boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydrous hexane at5° C.

FIG. 5. Evolution of the molar percentage (ordinate; without unit) ofthe different boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydrous chloroformat 5° C.

FIG. 6. Evolution of the molar percentage (ordinate; without unit) ofthe different boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydroustetrahydrofuran at 5° C.

FIG. 7. Evolution of the molar percentage (ordinate; without unit) ofthe different boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydrous chloroformat 5° C.

FIG. 8. Evolution of the molar percentage (ordinate; without unit) ofthe different boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydroustetrahydrofuran at 5° C. in the presence of 1 mol % of anhydroustriethylamine.

FIG. 9. Evolution of the molar percentage (ordinate; without unit) ofthe different boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydroustetrahydrofuran at 5° C. in the presence of 1 mol % of anhydrous benzoicacid.

FIG. 10. Evolution of the molar percentage (ordinate; without unit) ofthe different boronic esters in time (abscissa; minutes) during themetathesis between the two alkylboronic esters in anhydroustetrahydrofuran at room temperature

FIG. 11. Evolution of the molar percentage (ordinate; without unit) ofthe different boronic esters in time (abscissa; minutes) during themetathesis between boronic esters containing respectively an aryldiolsubstituent and an alkyldiol substituent in anhydrous tetrahydrofuran atroom temperature.

FIG. 12. Evolution of the molar percentage (ordinate; without unit) ofthe different boronic esters in time (abscissa; minutes) during themetathesis between boronic esters containing respectively a1,2-alkyldiol substituent and a 1,3-alkyldiol substituent in anhydroustetrahydrofuran at room temperature.

FIG. 13. Evolution of the molar percentage (ordinate; without unit) ofthe two starting boronic esters and of the two boronic esters formedduring the metathesis reaction of phenylboronic esters MR-02-66 andMR-2016a in bulk at 60° C. as a function of time (abscissa; minutes)

FIG. 14. Evolution of the molar percentage (ordinate; without unit) ofthe two starting boronic esters and of the two boronic esters formedduring the metathesis reaction of phenylboronic esters MR-02-66 andMR-2016a in bulk at 85° C. as a function of time (abscissa; minutes)

FIG. 15. Evolution of the molar percentage (ordinate; without unit) ofthe two starting boronic esters and of the two boronic esters formedduring the metathesis reaction of phenylboronic esters MR-02-66 andMR-2016a in bulk at 150° C. as a function of time (abscissa; minutes)

FIG. 16. Stress at break (ordinate, MPa) of samples of the cross-linkedpolymer network N1 not recycled (abscissa, 0), of samples of thecross-linked polymer network N1 recycled 1 time (abscissa, 1), ofsamples of the cross-linked polymer network N1 recycled 2 times(abscissa, 2), of samples of the cross-linked polymer network N1recycled 3 times (abscissa, 3).

FIG. 17. Elongation at break (ordinate, %) of samples of thecross-linked polymer network N1 not recycled (abscissa, 0), of samplesof the cross-linked polymer network N1 recycled 1 time (abscissa, 1), ofsamples of the cross-linked polymer network N1 recycled 2 times(abscissa, 2), of samples of the cross-linked polymer network N1recycled 3 times (abscissa, 3).

FIG. 18. Deformation (ordinate, %) as a function of time (abscissa,min), for 4 temperatures (160° C. circles; 150° C. triangles; 140°squares; 130° C. stars), of samples of the cross-linked polymer networkN1.

FIG. 19. Deformation (ordinate, %) in time (abscissa, min), at 160° C.of samples of the cross-linked polymer network N2.

FIG. 20. Shear relaxation modulus normalized by the initial modulus att=0 (ordinate, without unit) as a function of time (abscissa, seconds)of samples of the cross-linked polymer network N1 at 170° C. (square),at 150° C. (circle), at 130° C. (triangle).

FIG. 21. Shear relaxation modulus normalized by the initial modulus att=0 (ordinate, without unit) as a function of time (abscissa, seconds)at 150° C., of samples of the cross-linked polymer network N1 (circle),of samples of the cross-linked polymer network N2 (triangle), of samplesof the cross-linked polymer network N3 (square).

FIG. 22. Shear relaxation modulus normalized by the initial modulus att=0 (ordinate, without unit) as a function of time (abscissa, seconds)of the samples of the cross-linked polymer networks NX1 at 150° C.(square)

FIG. 23. Shear relaxation modulus normalized by the initial modulus att=0 (ordinate, without unit) as a function of time (abscissa, seconds)of the samples of the cross-linked polymer networks NX2 at 150° C.(circle)

FIG. 24. Average stress at break (ordinate, MPa) of samples of thecross-linked polymer network NY1 not recycled (abscissa, 0), of samplesof the cross-linked polymer network NY1 recycled 1 time (abscissa, 1),of samples of the cross-linked polymer network NY1 recycled 2 times(abscissa, 2), of samples of the cross-linked polymer network NY1recycled 3 times (abscissa, 3).

FIG. 25. Average Young's modulus (ordinate, GPa) of samples of thecross-linked polymer network NY1 not recycled (abscissa, 0), of samplesof the cross-linked polymer network NY1 recycled 1 time (abscissa, 1),of samples of the cross-linked polymer network NY1 recycled 2 times(abscissa, 2), of samples of the cross-linked polymer network NY1recycled 3 times (abscissa, 3).

FIG. 26. Average tensile strength (ordinate, MPa) of samples of thecross-linked polymer network NZ1 not recycled (abscissa, 0), of samplesof the cross-linked polymer network NZ1 recycled 1 time (abscissa, 1),of samples of the cross-linked polymer network NZ1 recycled 2 times(abscissa, 2), of samples of the cross-linked polymer network NZ1recycled 3 times (abscissa, 3).

FIG. 27. Average Young's modulus (ordinate, GPa) of samples of thecross-linked polymer network NZ1 not recycled (abscissa, 0), of samplesof the cross-linked polymer network NZ1 recycled 1 time (abscissa, 1),of samples of the cross-linked polymer network NZ1 recycled 2 times(abscissa, 2), of samples of the cross-linked polymer network NZ1recycled 3 times (abscissa, 3).

FIG. 28. Schematic representation of the lab joints consisting of twosingle laps obtained by placing one strip of cross-linked PMMA networkN6 (dark grey) onto two separated strips of cross-linked HDPE networkNZ1 (light grey), with both overlap lengths l₀ equal to 1 cm.

FIG. 29. Force normalized by the width (ordinate, kN/m) as a function ofdisplacement (abscissa, mm) during the lap-shear testing of thecross-linked HDPE network NZ1/cross-linked PMMA network N6/cross-linkedHDPE network NZ1 lap joints glued for 10 min (solid line), respectively20 min (dash line), at 190° C.

DETAILED DESCRIPTION

Throughout the description, the term “exchangeable links” implies linksthat are exchangeable by boronic ester metathesis reactions. These linksmay be present in the pending links or in cross-links.

The object of the invention is a composition comprising (a) cross-linkedpolymers containing exchangeable pending links and exchangeablecross-links, by boronic ester metathesis reactions; and (b) freemonofunctional boronic esters, said boronic esters being chosen fromamong the following dioxaborolane and dioxaborinane rings of formulas(EB1) and (EB2):

-   -   in which    -   Rx, Rw and Rv are identical or different and each represent a        hydrogen atom or a hydrocarbon radical or form together, as a        pair, an aliphatic or aromatic ring    -   Ry is a hydrocarbon radical linked to the boron atom of the        dioxaborolane or dioxaborinane ring by a covalent bond through a        carbon atom.

This composition may be obtained by cross-linking of linear or branchedpolymers.

It may also be obtained by copolymerisation of the following compounds:

-   -   (a) Precursor monomers to thermoplastic polymers comprising at        least one pending boronic ester group, said pending boronic        ester group not containing any polymerisable group;    -   (b) Cross-linking agent comprising at least one boronic ester        group enabling the formation of a network of cross-linked        polymer containing pending functions and cross-links that are        exchangeable by boronic ester metathesis reactions;        -   said boronic esters being chosen from among the following            dioxaborolane and dioxaborinane rings of formulas (EB1) and            (EB2):

-   -   -   in which        -   Rx, Rw and Rv are identical or different and each represent            a hydrogen atom or a hydrocarbon radical or form together,            as a pair, an aliphatic or aromatic ring        -   Ry is a hydrocarbon radical linked to the boron atom of the            dioxaborolane or dioxaborinane ring by a covalent bond            through a carbon atom.

    -   (c) possibly monomers that are precursors to thermoplastic        polymers that do not include a boronic ester group of formula        (EB1) or (EB2).

The expression “said boronic esters” refers to the boronic esterspresent in the exchangeable pending links, in the exchangeablecross-links and in the free monofunctional boronic esters.

Preferably, independently for each boronic ester group, Rx, Rw and Rvare identical or different and each represents an alkyl, aryl, aralkylalkyl-aryl or cycloalkyl group. This radical can contain heteroatoms, inparticular chosen from among O, N, S or Si, and/or may be substituted.In particular, independently for each boronic ester group, Rx and/or Rwand/or Rv form together, in pairs, an aliphatic or aromatic ring.

In particular, these radicals Rx, Rw and Rv may be substituted byfunctional groups such as ester or amide functions. In particular, theseradicals may be substituted by a halogen, an -Rz, —OH, —NH2, —NHRz,—NRzR′z, —C(O)—H, —C(O)—Rz, —C(O)—OH, —C(O)—NRzR′z, —C(O)—O-Rz,—O—C(O)-Rz, —O—C(O)—O-Rz, —O—C(O)—N(H)-Rz, —N(H)—C(O)—O-Rz, —O-Rz, —SH,—S-Rz, —S—S-Rz, —C(O)—N(H)-Rz, —N(H)—C(O)-Rz group with Rz, R′z,identical or different, representing a C₁-C₅₀ alkyl radical. Inparticular, these radicals Rx, Rw and Rv may include ester, amide,ether, thioether, secondary or tertiary amine, carbonate, urethane,carbamide or anhydride functions.

In particular, independently for each boronic ester group, Ry representsan alkyl, aryl, aralkyl, alkyl-aryl or cycloalkyl radical. This radicalcan contain heteroatoms, in particular chosen from among O, N, S or Si,and/or may be substituted. In particular, this radical Ry may besubstituted by functional groups such as ester or amide functions. Inparticular, this radical is substituted by a halogen, an -Rz, —OH, —NH2,—NHRz, —NRzR′z, —C(O)—H, —C(O)—Rz, —C(O)—OH, —C(O)—NRzR′z, —C(O)—O-Rz,—O—C(O)-Rz, —O—C(O)—O-Rz, —O—C(O)—N(H)-Rz, —N(H)—C(O)—O-Rz, —O-Rz, —SH,—S-Rz, —S—S-Rz, —C(O)—N(H)-Rz, —N(H)—C(O)-Rz group with Rz, R′z,identical or different, representing a C₁-C₅₀ alkyl radical. Inparticular, this radical Ry may include ester, amide, ether, thioether,secondary or tertiary amine, carbonate, urethane, carbamide or anhydridefunctions.

These boronic ester groups are preferably linked, through Rx and/or Ry,to a polymer chain or to a functional group G enabling covalent linkageof molecules to polymer chains to be functionalised, as defined below.When their substituents {Rx, Rw} or {Rx, Rv} together form and aliphaticor aromatic ring, the boronic ester groups may be linked, through theirsubstituents {Rx, Rw} or {Rx, Rv} and/or Ry, to a polymer chain or to afunctional group G enabling covalent linkage of molecules to polymerchains to be functionalised, as defined below.

The compositions according to the invention contain less than 2 mmol,more preferably less than 1.5 mmol, still more preferably less than 1mmol, still more preferably less than 0.8 mmol, still more preferablyless than 0.6 mmol, still more preferably less than 0.4 mmol, still morepreferably less than 0.2 mmol, still more preferably less than 0.1 mmol,still more preferably less than 0.05 mmol, still more preferably lessthan 0.025 mmol, still more preferably less than 0.02 mmol, still morepreferably less than 0.01 mmol, still more preferably less than 0.005mmol of 1,2-diol functions and/or 1,3 diol functions per gram of polymerafter cross-linking.

1. Preparation of the Composition by Cross-Linking of a Polymer:

Preferably, the cross-linking step does not require the use of polymersor additives containing 1,2-diol functions and/or 1,3-diol functions.Cross-linking results, partially or totally, from metathesis reactionsbetween the ester functions on the pending groups of the polymers and/oron the pending groups in the polymers and on compounds of formula (Ia)or (Ib), defined below. In this way, for every cross-linking reaction bymetathesis reaction between boronic ester functions, one equivalent offree monofunctional boronic ester is generated, as illustrated in FIG. 3in the case of cross-linking by a metathesis reaction of linear polymersfunctionalised by complementary pending dioxaborolane functions. Such acomposition preferably forms a network of linear or branched polymerscontaining pending links and crosslinks that are exchangeable by boronicester metathesis reactions. Such a composition preferably contains lessthan 2 mmol, more preferably less than 1.5 mmol, still more preferablyless than 1 mmol, still more preferably less than 0.8 mmol, still morepreferably less than 0.6 mmol, still more preferably less than 0.4 mmol,still more preferably less than 0.2 mmol, still more preferably lessthan 0.1 mmol, still more preferably less than 0.05 mmol, still morepreferably less than 0.025 mmol, still more preferably less than 0.02mmol, still more preferably less than 0.01 mmol, still more preferablyless than 0.005 mmol of 1,2-diol functions and/or 1,3 diol functions pergram of polymer after cross-linking.

Preferably, the polymers, before cross-linking, are linear or branchedpolymers having side-groups carrying:

-   -   pending boronic ester functional groups of formula (EB1) or        (EB2) linked to the polymers by at least one carbon atom of the        dioxaborolane or dioxaborinane ring; or    -   pending boronic ester functional groups of formula (EB1) or        (EB2) linked to the polymers by the boron atom of the        dioxaborolane or dioxaborinane ring.

These polymers can be functionalised prior to and/or duringcross-linking preferably leading to the formation of a network ofcross-linked polymers containing pending links and cross-links that areexchangeable by boronic ester metathesis reactions.

The side-groups that are exchangeable by boronic ester metathesisreactions of linear or branched polymers may be distributed along thewhole chain in a homogenous or non-homogenous manner or maybeconcentrated in one segment of the polymer chain. Preferably, theside-groups that are exchangeable by boronic ester metathesis reactionsof linear or branched polymers are distributed along the whole chain ina homogenous or non-homogenous manner. Preferably, the side-groups thatare exchangeable by boronic ester metathesis reactions of linear orbranched polymers are distributed in a segment or block of the polymerchain. This case is called a diblock structure. Preferably, the sidegroups that are exchangeable by boronic ester metathesis reactions arerandomly distributed all along the polymer chain. Preferably, thepolymer has a multiblock structure with blocks containing the sidegroups that are exchangeable by boronic ester metathesis reactionsdistributed all along the polymer chain.

The polymers before cross-linking preferably contain less than 4 mmol,more preferably less than 3 mmol, still more preferably less than 2mmol, still more preferably less than 1.5 mmol, still more preferablyless than 1 mmol, still more preferably less than 0.8 mmol, still morepreferably less than 0.6 mmol, still more preferably less than 0.5 mmol,still more preferably less than 0.4 mmol, still more preferably lessthan 0.25 mmol, still more preferably less than 0.2 mmol, still morepreferably less than 0.1 mmol, still more preferably less than 0.05 mmolof 1,2-diol functions and/or 1,3 diol functions per gram of polymer.

In a first embodiment, the polymer is functionalised beforecross-linking. In particular, the composition results from the mixture,in the molten state or in solution:

-   -   Of at least one linear or branched polymer P1 with side-groups        carrying:        -   boronic ester functional groups of formula (EB1) or (EB2)            linked to the polymer by at least one carbon atom of the            dioxaborolane or dioxaborinane ring; or        -   boronic ester functional groups of formula (EB1) or (EB2)            linked to the polymer by the boron atom of the dioxaborolane            or dioxaborinane ring.    -   Of at least one additive carrying at least two boronic ester        groups of formula (EB1) or (EB2) that are capable of reacting        with the pending groups of the polymer P1 to form a cross-linked        polymer composition, preferably a cross-linked network,        containing pending links and cross-links that are exchangeable        by boronic ester metathesis reactions.

To enable the formation of a cross-linked polymer composition,preferably a cross-linked polymer network, a cross-linking agent thatwill not, on its own, react with itself and lose its functionality, ispreferably used as an additive. In this way, the cross-linking agentcarries:

-   -   boronic ester functions of formula (EB1) or (EB2) linked to the        agent by at least one carbon atom of the dioxaborolane or        dioxaborinane ring; or    -   boronic ester functions of formula (EB1) or (EB2) linked to the        agent by the boron atom of the dioxaborolane or dioxaborinane        ring.

The additive (the cross-linking agent) may be a molecule and/or apolymer. Combinations of molecules and/or of polymers may be envisaged.

In a first embodiment, the additive is a molecule having at least twoboronic ester functions of formula (EB1) or (EB2). This additive is alsocalled a “bi- or multifunctional cross-linking agent”. This additive caninclude boronic ester functions of formula (EB1) or (EB2) all linked tothe rest of the molecule by at least one carbon atom of thedioxaborolane or dioxaborinane ring, or boronic ester functions alllinked to the rest of the molecule by the boron atom of thedioxaborolane or dioxaborinane ring.

This additive is preferably a compound of formula (Ia), (Ib1) or (Ib2)below:

-   -   in which    -   n is a whole number between 1 and 6;    -   i is a whole number between 1 and n;    -   k equals 0 or 1; each ki equals 0 or 1. In this way, the boronic        ester functions carried by the compounds of formula (Ia) and        (Ib) may be dioxaborolane and/or dioxaborinane functions.    -   R₁, R′₁, R″₁, R_(3i), R′_(3i), R″_(3i), R₅, R″₅, R_(7i),        R″_(7i), identically or differently, each represent,        independently from one another, a hydrogen atom or a hydrocarbon        group;    -   {R₁, R′₁, R″₁} can together form, in pairs, an aliphatic or        aromatic ring    -   {R_(3i), R′_(3i), R″_(3i)} can together form, in pairs, an        aliphatic or aromatic ring    -   {R₅, R″₅} can together form an aliphatic or aromatic ring    -   {R_(7i), R″_(7i)} can together form an aliphatic or aromatic        ring    -   R₂ and R₄, identical or different, each represent a hydrocarbon        group R₂ is linked to the boronic ester function through a        carbon atom    -   R₆, R_(8i), identical or different, each represent,        independently of one another, a hydrocarbon group; R₆, each        R_(8i) is linked to the boron atom by a covalent bond through a        carbon atom.

Hereinafter, the terms (Ib) designate either the formula (Ib1) or theformula (Ib2).

R₂ and R₄, identical or different, can in particular represent a ring,hence allowing the presence of several blocks [boronic ester], possiblyon each carbon atom of the ring.

The block [boronic ester] is present n times, depending on the number ofsubstitutions possible on the radicals R₂ and R₄. The compounds (Ia) and(Ib) can therefore be “star” compounds.

n is a whole number between 1 and 6, preferably between 1 and 4.

i is a whole number between 1 and n.

From one block to another (and likewise for different values of i), thedefinition of ki, R₃, R′_(3i), R″_(3i), R_(7i) and R″_(7i) may vary,which means that the blocks are not necessarily identical to each other.

R₂ and R₄, identical or different, are each preferably an aliphatic,aromatic, arylaliphatic or cycloaliphatic group that may also containheteroatoms such as O, N, S, or Si. In a preferred embodiment, R₂ andR₄, identical or different, each represent an aromatic or heteroaromaticgroup. Preferably, R₂ and R₄, identical or different, each represent aC₁-C₁₂ alkanediyl group, a benzene ring, a naphthalene ring, anarylaliphatic group comprising two benzene rings linked by a C₁-C₆alkanediyl group, a pyrimidine ring or a triazine ring.

R₁, R′₁, R″₁, R_(3i), R′_(3i), R″_(3i), R₅, R″₅, R_(7i) and R″_(7i),identical or different, preferably represent a hydrogen atom or analkyl, alkenyl, aryl, cycloalkyl, heteroaryl, heteroalkyl orheterocycloalkyl group, and each of these groups may be substituted, orR₁, R′₁, R″₁, or R_(3i), R′_(3i), R″_(3i), or R₅, R″₅, or R_(7i),R″_(7i), together form, in pairs, an aliphatic or aromatic ring.

The use of a compound of formula (Ia) or of a compound of formula (Ib)to obtain a composition comprising cross-linked polymers, preferably across-linked network, containing pending links and cross-links that areexchangeable by boronic ester metathesis reactions and freemonofunctional boronic esters of formula (EB1) or (EB2) will depend onthe nature of the atom through which the pending boronic esterfunctional groups are linked to the polymer P1.

In this way, when the pending boronic ester groups of formula (EB1) or(EB2) are linked to the polymer P1 by at least one carbon atom of thedioxaborolane or dioxaborinane ring, a compound of formula (Ia) ischosen as the additive.

In this way, when the pending boronic ester groups of formula (EB1) or(EB2) are linked to the polymer P1 by the boron atom of thedioxaborolane or dioxaborinane ring, a compound of formula (Ib) ischosen as the additive.

In a second embodiment, the additive is a polymer P2 carrying:

-   -   boronic ester functional groups of formula (EB1) or (EB2) linked        to the polymer by at least one carbon atom of the dioxaborolane        or dioxaborinane ring; or    -   boronic ester functional groups of formula (EB1) or (EB2) linked        to the polymer by the boron atom of the dioxaborolane or        dioxaborinane ring.

The choice of nature of the atom through which the pending boronic esterfunctional groups are linked to the polymer P2 will depend on the natureof the atom through which the pending boronic ester functional groupsare linked to the polymer P1.

In this way, when the pending boronic ester groups are linked to thepolymer P1 by at least one carbon atom of the dioxaborolane ordioxaborinane ring, a polymer containing pending boronic esterfunctional groups linked to the polymer P2 by the boron atom of thedioxaborolane or dioxaborinane ring is chosen as the polymer P2.

In this way, when the pending boronic ester groups are linked to thepolymer P1 by the boron atom of the dioxaborolane or dioxaborinane ring,a polymer containing pending boronic ester functional groups linked tothe polymer P2 by at least one carbon atom of the dioxaborolane ordioxaborinane ring is chosen as the polymer P2.

Hence the invention enables two linear or branched polymers to beassembled by boronic ester metathesis reactions, even if the chemicalnatures of the polymers are different or incompatible. In this way theinvention enables two thermosetting polymers to be assembled. Theassembly of a polymer composition according to the invention with alinear or branched polymer P2 may also be envisaged along the sameprinciple. This principle can even be extended to two compositionsaccording to the invention, which can be assembled.

In a second embodiment, the functionalisation and the cross-linking arecarried out simultaneously.

In particular, the composition results from the mixture, in the moltenstate or in solution:

-   -   Of at least one linear or branched polymer P1′ containing        functions enabling grafting,    -   A combination of molecules of which the molecules comprise at        one end a functional group enabling covalent binding of the        molecule to the polymer P1′ and at the other end a functional        group chosen from among a dioxaborolane or dioxaborinane boronic        ester function linked to the rest of the molecule by at least        one carbon atom of the dioxaborolane or dioxaborinane ring (A),        a boronic ester function of formula (EB1) or (EB2) linked to the        rest of the molecule by its boron atom of the dioxaborolane or        dioxaborinane ring (B), and/or molecules comprising at two of        their extremities functional groups enabling covalent binding of        the molecule to the polymer P1′ and between these two        extremities a boronic ester function of formula (EB1) or (EB2)        (C), the combination enabling grafting and the creation of        pending links and cross-links that are exchangeable by boronic        ester metathesis reactions.

In this way, the polymer P1′ may be functionalised and cross-linked onaddition of the additive. For this, the polymer contains functionsenabling grafting, for example in its main chain or on its side/pendinggroups.

FIG. 1 shows molecules that may be used for the functionalisation andone-step cross-linking of the polymers. The letters G₁, G₂, G₃ and G₄represent a functional group enabling the covalent binding of themolecules to the polymer chain to be functionalised. The functionalgroups G₁, G₂, G₃ and G₄ are chosen as a function of the polymers to befunctionalised, the functions enabling grafting to these polymers andthe grafting conditions (temperature, reaction medium (molten state orin solution), kinetics, use of a catalyst, etc.). Preferably the groupsG₁, G₂, G₃ and G₄ are identical.

As non-limiting examples, the functions G may be thiol functionsenabling the functionalisation of the alkene bonds of polydienes, suchas polybutadiene, polyisoprene and their copolymers, vinyl copolymerswith pending alkene groups, or polyolefins obtained by ring-openingmetathesis polymerisation (ROMP) or by acyclic diene metathesis (ADMET)(Charles E. Hoyle, Christopher N. Bowman, Angew. Chem. Int. Ed. 2010,49, 1540-1573; Kemal Arda Gunay, Patrick Theato, Harm-Anton Klok,Journal of Polymer Science Part A: Polymer Chemistry 2013, 51, 1-28).The functions G may also be maleimide or methacrylic, acrylic, styrenicor maleic ester functions so as to enable radical grafting topolyethylene and polypropylene for example (G. Moad, Prog. Polym. Sci.1999, 24, 81-142; Elisa Passagliaa, Serena Coiai, Sylvain Augier, Prog.Polym. Sci. 2009, 34, 911-947). The functions G may be isocyanatefunctions that will react with the pending alcohol, amine or thiolgroups on the polymers to be functionalised (Kemal Arda Gunay, PatrickTheato, Harm-Anton Klok, Journal of Polymer Science Part A: PolymerChemistry 2013, 51, 1-28; Charles E. Hoyle, Andrew B. Lowe, ChristopherN. Bowman, Chem. Soc. Rev., 2010, 39, 1355-1387). The functions G mayalso be electrophilic olefins that can undergo Michael additions withnucleophiles such as thiols, primary or secondary amines or phosphines(Brian D. Mather, Kalpana Viswanathan, Kevin M. Miller, Timothy E. Long,Prog. Polym. Sci. 2006, 31, 487-531). Among the electrophilic olefins,non-limiting examples include acrylates, acrylamides, maleimides,methacrylates and vinylic sulfones. The functions G may also benucleophilic functions such as alcohols, thiols, amines or carboxylicacids, which can give nucleophilic substitution or ring-openingreactions (Kemal Arda Gunay, Patrick Theato, Harm-Anton Klok, Journal ofPolymer Science Part A: Polymer Chemistry 2013, 51, 1-28). Thesefunctional groups can, for example, open epoxides present in the mainchain of the polymers, such as are found in epoxidised natural rubber,or pending epoxide functions such as are found in vinylic copolymersprepared with glycidyl methacrylate. The functions G may also bealcohol, thiol or amine functions that can react with pending ester oractivated ester functions to give new ester, thioester or amidefunctions. This approach can notably be used to functionalise vinylicpolymers with pending ester functions, such as for example poly(methylmethacrylate). The functional groups enabling the molecule containingthe boronic ester function to be covalently linked to the polymer P1′are therefore numerous and varied, and the person skilled in the artknows how to select the functional group of choice depending on thefunctions present on the polymer P1′ and the grafting conditions(temperature, reaction medium (molten state or in solution), kinetics,use of a catalyst, etc.).

FIG. 1 defines molecules (A), (B) and (C), where the letters G₁, G₂, G₃and G₄ represent a functional group enabling the molecules to becovalently linked to polymer chains to be functionalised, Rx, R″x, andRy, R′y, R″y are hydrocarbon groups, R′v, R′w and R′x, identical ordifferent, each represent a hydrogen atom or a hydrocarbon radical, ortogether form, in pairs, an aliphatic or aromatic ring, Rv and Rw, andR″v and R″w, identical or different, represent a hydrogen atom or ahydrocarbon radical, or form an aliphatic or aromatic ring together, orwith Rx, respectively or with R″x. The hydrocarbon groups Ry, R′y andR″y are linked to the boron of the dioxaborolane and dioxaborinane ringthrough a carbon atom. The labels “Rx”, “Rw”, “Rv” and “Ry” are used byanalogy to the definition of the boronic esters according to theinvention, without necessarily being identical.

In particular, Rx, R′x and R″x each represent, independently of oneanother, an aliphatic, aromatic, arylaliphatic or cycloaliphaticradical. This radical can contain heteroatoms, in particular chosen fromamong O, N, S or Si, and/or may be substituted.

In particular, Rx, R′x and R″x, independently of one another, may eachbe substituted by functional groups such as ester or amide functions. Inparticular, this radical is substituted by a halogen, an -Rz, —OH, —NH2,—NHRz, —NRzR′z, —C(O)—H, —C(O)—Rz, —C(O)—OH, —C(O)—NRzR′z, —C(O)—O-Rz,—O—C(O)-Rz, —O—C(O)—O-Rz, —O—C(O)—N(H)-Rz, —N(H)—C(O)—O-Rz, —O-Rz, —SH,—S-Rz, —S—S-Rz, —C(O)—N(H)-Rz, —N(H)—C(O)-Rz group with Rz, R′z,identical or different, representing a C₁-C₅₀ alkyl radical. Inparticular, this radical Rx, R′x or R″x may include ester, amide, ether,thioether, secondary or tertiary amine, carbonate, urethane, carbamideor anhydride functions.

In particular, Ry, R′y and R″y each represent, independently of oneanother, an aliphatic, aromatic, arylaliphatic or cycloaliphatic radicallinked to the boron atom of the dioxaborolane or dioxaborinane ringthrough a carbon atom. This radical Ry, R′y or R″y can containheteroatoms, in particular chosen from among O, N, S or Si, and/or maybe substituted. In particular, this radical Ry, R′y or R″y may besubstituted by functional groups such as ester or amide functions. Inparticular, this radical Ry, R′y or R″y is substituted by a halogen, an-Rz, —OH, —NH2, —NHRz, —NRzR′z, —C(O)—H, —C(O)—Rz, —C(O)—OH,—C(O)—NRzR′z, —C(O)—O-Rz, —O—C(O)-Rz, —O—C(O)—O-Rz, —O—C(O)—N(H)-Rz,—N(H)—C(O)—O-Rz, —O-Rz, —SH, —S-Rz, —S—S-Rz, —C(O)—N(H)-Rz,—N(H)—C(O)-Rz group with Rz, R′z, identical or different, representing aC₁-C₅₀ alkyl radical. In particular, this radical Ry, R′y or R″y mayinclude ester, amide, ether, thioether, secondary or tertiary amine,carbonate, urethane, carbamide or anhydride functions.

FIG. 2 schematically shows the functionalisation of linear polymers bymolecule A in the case of a dioxaborolane cyclic boronic ester, or B inthe case of a dioxaborolane cyclic boronic ester, through the creationof covalent bonds between molecule A, or B, and the polymer chains.

The combinations enabling the one-step cross-linking andfunctionalisation of polymers are:

-   -   A+B: Polymers functionalised with pending boronic ester        functions of formula (EB1) or (EB2) attached to the polymer by        at least one carbon atom of the dioxaborolane or dioxaborinane        ring (A)+polymers functionalised with pending boronic ester        functions of formula (EB1) or (EB2) attached to the polymer by        the boron atom of the dioxaborolane or dioxaborinane ring (B)        and cross-linking by boronic ester metathesis reaction, as        illustrated in FIG. 3 in the case of dioxaborolane cyclic        boronic esters. Metathesis reactions between boronic esters can        take place between A and B before these functions graft onto the        polymers (which generates a molecule equivalent to molecule C        plus a free monofunctional boronic ester).    -   A+C: Polymers cross-linked by molecule (C)+polymers        functionalised with pending boronic ester functions of formula        (EB1) or (EB2) attached to the polymer by at least one carbon        atom of the dioxaborolane or dioxaborinane ring (A). Metathesis        reactions between boronic esters can take place between A and C        before these functions graft onto the polymers.    -   B+C    -   A+B+C

In summary, any combination in which on average at least two boronicester functions will be grafted per polymer chain and linked to the mainchain by at least one carbon atom of the dioxaborolane or dioxaborinanering and two boronic ester functions will be grafted per polymer chainand linked to the main chain by the boron atom of the dioxaborolane ordioxaborinane ring.

Other combinations are possible when a compound of formula (Ia) or (Ib),defined above, are used:

-   -   A+compound (Ia). In this way, polymers functionalised with        pending boronic ester functions of formula (EB1) or (EB2) linked        to the main chain by at least one carbon atom of the        dioxaborolane or dioxaborinane ring (A) are prepared, then        cross-linking is carried out by a boronic ester metathesis        reaction between the pending functions and compound (Ia).        Metathesis reactions between boronic esters can take place        between A and compound (Ia) before these functions graft onto        the polymers.    -   B+compound (Ib)

Again, there must be on average at least two pending exchangeablefunctions grafted per polymer chain (through A or B). The quantity ofcompound (Ia) or of compound (Ib) will vary according to itsfunctionality. Nevertheless, it can be said that compounds (Ia) and (Ib)must also supply on average at least two boronic ester functions offormula (EB1) or (EB2) per polymer chain. These functions must becomplementary to the functions grafted onto the polymers (through A orB).

In the compositions according to the invention, the polymers includepending boronic ester functions of formula (EB1) or (EB2). They alsoinclude boronic ester functions of formula (EB1) or (EB2) in some,preferably all, of their side-chains forming cross-links. This enablesan exchange between boronic esters and improves the cross-linking of thepolymers. The inventors think that the exchange reactions betweenboronic esters enables a circulation of cross-links and could explainthe thermoplastic behaviour when the composition, in itself, isinsoluble like a thermoset.

The compositions also include free monofunctional esters of formula(EB1) or (EB2) formed during the creation of cross-links.

A compound having a single boronic ester function of formula (EB1) or(EB2) may also be added to any of the compositions previously described.This additional compound enables the properties, notably the viscosity,of the polymer compositions to be modulated.

The polymer P1, or P1′, and if applicable the polymer P2, is preferablya thermoplastic polymer or a thermosetting polymer.

By the process according to the invention, polymer preparations havingthe properties of thermosets and thermoplastics may be prepared from anythermoplastic polymer.

The polymer may be chosen from among:

-   -   vinylics, in particular polystyrenes, poly(meth)acrylates,        poly(meth)acrylamides, polydienes such as polyisoprenes and        polybutadienes, poly(vinyl chloride)s, polyfluorinated polymers,        poly(vinyl acetate)s, polyvinylpyrrolidone or        polyvinylcarbazole,    -   polyolefins, in particular polyethylene and polypropylene,    -   unsaturated polyolefins,    -   polyamides,    -   polysaccharides,    -   polysiloxanes or silicones.

These polymers may be functionalised to introduce pending boronic esterfunctionalised side groups of formula (EB1) or (EB2) or to introducegroups or functions enabling grafting. The introduction of these pendingboronic ester functionalised side groups can be carried out by variousprocesses known to the person skilled in the art: copolymerisation ofpolymer-precursor monomers with boronic ester functionalised monomers(the boronic ester functions are not integrated into the main chain ofthe polymer being formed, but are found on a pending side group),grafting onto a reactive function of the polymer, copolymerisation ofpolymer-precursor monomers with monomers containing one or morefunctions that will serve to graft the pending boronic ester functionsafter formation of the polymer. These functions that will serve to graftthe pending boronic ester functions may be functions that are notimplicated in the polymerisation reaction or may be functions that areimplicated in the polymerisation reaction but that remain unreacted atthe end of polymerisation, either because of thestoichiometry/functionality of the monomer mix or because thepolymerisation stopped before the complete conversion of all thepolymerisable functions. Such processes are known to the person skilledin the art and are notably used in the synthesis of polymers bypolycondensation and by polyaddition. For example, the polymer P1 isobtained by copolymerisation, by a radical route or by polycondensation,by polymerisation by coordination, or by polyaddition or by ring-openingof a monomer precursor to a thermoplastic polymer and of a monomercarrying the boronic ester functionalised side group. For example, thepolymer P1′ is obtained by copolymerisation, by a radical route or bypolycondensation, by polymerisation by coordination, or by polyadditionor by ring-opening of a monomer precursor to a thermoplastic polymer andof a monomer carrying the side group enabling the grafting of themolecule containing the boronic ester function. Likewise, theintroduction of groups or functions enabling grafting can be carried outby various processes known to the person skilled in the art (Charles E.Hoyle, Christopher N. Bowman, Angew. Chem. Int. Ed. 2010, 49, 1540-1573;Kemal Arda Gunay, Patrick Theato, Harm-Anton Klok, Journal of PolymerScience Part A: Polymer Chemistry 2013, 51, 1-28; G. Moad, Prog. Polym.Sci. 1999, 24, 81-142; Elisa Passagliaa, Serena Coiai, Sylvain Augier,Prog. Polym. Sci. 2009, 34, 911-947; Charles E. Hoyle, Andrew B. Lowe,Christopher N. Bowman, Chem. Soc. Rev., 2010, 39, 1355-1387; Brian D.Mather, Kalpana Viswanathan, Kevin M. Miller, Timothy E. Long, Prog.Polym. Sci. 2006, 31, 487-531; T. C. Chung, Prog. Polym. Sci. 2002, 27,39-85. Chulsung Bae, John F. Hartwig, Hoyong Chung, Nicole K. Harris,Karen A. Switek, Marc A. Hillmyer, Angew. Chem. Int. Ed. 2005, 44,6410-6413).

As described above, the polymers may be functionalised and cross-linkedon addition of the additive.

The number average molar mass, M of the linear or branched polymers P1,P1′, or P2, i.e. before cross-linking, is preferably between 2000 g/moland 2500000 g/mol, more preferably between 5000 g/mol and 750000 g/moland still more preferably between 10000 g/mol and 400000 g/mol.

The dispersity, Ð=M_(w)/M_(n), of the linear or branched polymers P1,P1′, or P2, i.e before cross-linking, is preferably between 1.01 and 15,more preferably between 1.03 and 10 and still more preferably between1.05 and 7.5.

In the invention, the molar ratio of [repetition units of polymer P1 orP1′ not containing pending boronic ester functions]/[repetition units ofpolymer P1 or P1′ containing pending boronic ester functions] ispreferably between 0.01 and 1000, more preferably between 0.1 and 250,and still more preferably between 1 and 100. “Pending boronic esterfunctions” means here either a boronic ester function or a function thatenables the grafting of such a boronic ester function.

The molar ratio [compound of formula (Ia)]/[repetition unit of polymerP1 or P1′ containing a pending boronic ester function] is preferablybetween 5 and 0.001, more preferably between 1 and 0.005, and still morepreferably between 0.5 and 0.01. “Pending boronic ester functions” meanshere either a boronic ester function or a function that enables thegrafting of such a boronic ester function.

The molar ratio [compound of formula (Ib)]/[repetition unit of polymerP1 or P1′ containing a pending boronic ester function] is preferablybetween 5 and 0.001, more preferably between 1 and 0.005, and still morepreferably between 0.5 and 0.01. “Pending boronic ester functions” meanshere either a boronic ester function or a function that enables thegrafting of such a boronic ester function.

In the invention, the molar ratio of [repetition units of polymer P2 notcontaining pending boronic ester functions]/[repetition units of polymerP2 containing pending boronic ester functions] is preferably between0.01 and 1000, more preferably between 0.1 and 250, and still morepreferably between 1 and 100.

The molar ratio [repetition unit of polymer P2 containing a pendingboronic ester function]/[repetition unit of polymer P1 or P1′ containinga pending boronic ester function] is preferably between 2500 and 0.0004,more preferably between 250 and 0.004, and still more preferably between100 and 0.01. “Pending boronic ester functions” means here either aboronic ester function or a function that enables the grafting of such aboronic ester function.

The physical and chemical properties of the polymers of the inventiondepend strongly on the compounds used, in particular on the polymers P1and P1′, and if applicable P2.

Nevertheless, starting from a thermoplastic polymer P1 or P1′, thecompositions according to the invention combine the properties of athermoplastic polymer with those of a thermoset. In particular, thecompositions according to the invention are insoluble like a thermosetbut may be recycled and/or reshaped at a temperature higher than theglass transition temperature (Tg) or the melting temperature (Tf) of thepolymer P1 or P1′, if applicable P2, preferably higher than Tg or Tf+10°C., more preferably higher than Tg or Tf+20° C., still more preferablyhigher than Tg or Tf+40° C., still more preferably higher than Tg orTf+80° C., if the glass transition temperature or the meltingtemperature is lower than 25° C.

2. Preparation of the Composition by Copolymerisation of Monomers:

The object of the invention is a polymer composition comprising anetwork of cross-linked polymers. Said network is prepared bycopolymerisation of the following compounds:

-   -   (a) Precursor monomers to thermoplastic polymers comprising at        least one pending boronic ester group, said pending boronic        ester group not containing any polymerisable group;    -   (b) Cross-linking agent comprising at least one boronic ester        group enabling the formation of a network of cross-linked        polymer containing pending functions and cross-links that are        exchangeable by boronic ester metathesis reactions;    -   said boronic esters being chosen from among the following        dioxaborolane and dioxaborinane rings of formulas (EB1) and        (EB2):

-   -   -   in which        -   Rx, Rw and Rv are identical or different and each represent            a hydrogen atom or a hydrocarbon radical or form together,            as a pair, an aliphatic or aromatic ring        -   Ry is a hydrocarbon radical linked to the boron atom of the            dioxaborolane or dioxaborinane ring by a covalent bond            through a carbon atom.

    -   (c) if applicable monomers that are precursors to thermoplastic        polymers that do not include a boronic ester group of formula        (EB1) or (EB2).

The polymerisation is preferably a radical polymerisation, apolymerisation by coordination, a ring-opening polymerisation, apolyaddition or a polycondensation.

Monomer (a):

Monomer (a), which is a boronic ester functional compound, includes atleast one pending boronic ester function of formula (EB1) or (EB2) permonomer and carries at least one polymerisable functional group. Thepending boronic ester function does not include a polymerisable group.

The expression “monomers comprising at least one pending boronic estergroup, said group not containing a polymerisable group” signifies thatthe pending boronic ester group is of formula (EB1) or (EB2) and thatnone of Rx, Rw, Rv or Ry carry a polymerisable group other than that orthose that constitute the monomer.

The expression “said pending boronic ester group not containing apolymerisable group” implies no group that is polymerisable through thepolymerisation mechanism used for the system considered.

The polymerisable functional group is preferably a functional group thatis polymerisable by radical polymerisation, by polymerisation bycoordination, by ring-opening polymerisation, by polyaddition or bypolycondensation. As examples, alcohol, epoxide, carboxylic acid, ester,primary or secondary amine, isocyanate or vinylic functions may bementioned.

Monomer (a) preferably includes only one or two polymerisable groups. Inparticular:

-   -   monomer (a) includes a single polymerisable group when the group        is polymerisable by radical polymerisation, by polymerisation by        coordination, or by ring-opening polymerisation    -   monomer (a) includes only two polymerisable groups when the        groups are polymerisable by polyaddition or by polycondensation.

Monomer (a) preferably has the formula (IIa) or (IIb) below:

In whichR₂₁, R′₂₁, R″₂₁, R₂₅, R″₂₅, identical or different, each represent,independently of one another, a hydrogen atom or a hydrocarbon groupR₂₆ represents a hydrocarbon groupR₂₂ and R₂₄ identical or different, each represent a hydrocarbon groupR₂₂ is linked to the boronic ester function by a covalent bond through acarbon atom{R₂₁, R′₂₁, R″₂₁} can together form, in pairs, an aliphatic or aromaticring{R₂₄, R₂₅, R″₂₅} can together form, in pairs, an aliphatic or aromaticringR₂₆ is linked to the boron atom by a covalent bond through a carbon atomk equals 0 or 1GFP₂ represents a polymerisable functional group as describedpreviously.m₂ equals 1 or 2.

Hereinafter, the terms (IIb) designate either the formula (IIb1) or theformula (IIb2).

Preferably, m₂ equals 2 when GFP₂ is polymerisable by polyaddition or bypolycondensation.

Preferably, m₂ equals 1 when GFP₂ is polymerisable by radicalpolymerisation, by polymerisation by coordination, or by ring-openingpolymerisation

None of the radicals R₂₁, R′₂₁, R″₂₁, R₂₂, R₂₄, R₂₅, R″₂₅, or R₂₆carries a functional group that is polymerisable by the mode ofpolymerisation used to polymerise GFP₂.

R₂₂ and R₂₄, identical or different, can in particular represent a ring,hence allowing the presence of several blocks [boronic ester], possiblyon each carbon atom of the ring or a hydrocarbon chain enabling thepresence of several blocks [boronic ester], possibly on different carbonatoms of the chain.

R₂₂ and R₂₄, identical or different, are each preferably an aliphatic,aromatic, arylaliphatic or cycloaliphatic group that may also containheteroatoms such as O, N, S, or Si. In a preferred embodiment, R₂₂ andR₂₄, identical or different, each represent an aromatic orheteroaromatic group.

Preferably, R₂₂ and R₂₄, identical or different, each represent aC₁-C_(u) alkanediyl group, a benzene ring, a naphthalene ring, anarylaliphatic group comprising two benzene rings linked by a C₁-C₆alkanediyl group, a pyrimidine ring or a triazine ring.

In particular, the radical RU or R₂₄ can contain heteroatoms, inparticular chosen from among O, N, S or Si, and/or may be substituted.In particular, this radical may be substituted by functional groups suchas ester or amide functions, on condition that these functional groupsare not involved in the polymerisation reactions. In particular, thisradical is substituted by a halogen, an -Rz, —OH, —NH2, —NHRz, —NRzR′z,—C(O)—H, —C(O)—Rz, —C(O)—OH, —C(O)—NRzR′z, —C(O)—O-Rz, —O—C(O)-Rz,—O—C(O)—O-Rz, —O—C(O)—N(H)-Rz, —N(H)—C(O)—O-Rz, —O-Rz, —SH, —S-Rz,—S—S-Rz, —C(O)—N(H)-Rz, —N(H)—C(O)-Rz group with Rz, R′z, identical ordifferent, representing a C₁-C₅₀ alkyl radical, insofar as this group isnot involved in the polymerisation reactions. In particular, thisradical may include ester, amide, ether, thioether, secondary ortertiary amine, carbonate, urethane, carbamide or anhydride functions.

R₂₁, R′₂₁, R″₂₁, R₂₅, R′₂₅, identical or different, preferably representa hydrogen atom or an alkyl, alkenyl, aryl, cycloalkyl, heteroaryl,heteroalkyl or heterocycloalkyl group, and each of these groups may besubstituted, or R₂₁, R′₂₁, R″₂₁, or R₂₄, R₂₅, R″₂₅, together form, inpairs, an aliphatic or aromatic ring.

As non-limiting examples, seven monomers (a), precursors tothermoplastic polymers comprising at least one pending boronic estergroup, are represented below, said pending boronic ester group notcontaining any polymerisable group in the system considered.

The monomers M1, M1OH M3 and M3COOH are precursors to polymethacrylatescomprising a pending dioxaborolane group, said pending dioxaborolanegroup not containing a polymerisable group. The polymerisation of thesemonomers is carried out by radical polymerisation. In this case, thealcohol and carboxylic acid functions respectively carried by thepending dioxaborolane groups of the monomers M1OH and M3COOH are notpolymerisable groups, as these functions are not involved in thepolymerisation reactions.

The monomer MX is a polyamide precursor comprising a pendantdioxaborolane group linked to the monomer by the boron atom. In thiscase, the primary amine function is a function that can only give riseto a single condensation reaction. The monomer MY is a precursor tothermoplastic polyepoxide when it is copolymerised with a diepoxidemonomer, comprising a pendant dioxaborolane group linked to the monomerby the boron atom. In this case, the primary amine function is afunction that can give rise to two condensation reactions on epoxiderings.

The monomer MZ is a polyester and polyurethane precursor comprising apendant dioxaborolane group linked to the monomer by the boron atom. Thesynthesis of polyesters is carried out by polycondensation betweenmonomers carrying alcohol functions and for example monomers carryingcarboxylic acid or ester function (these functions are not limiting andare not the only functions that can be used for the synthesis ofpolyesters). The synthesis of polyurethanes is carried out bypolyaddition between monomers carrying alcohol functions and monomerscarrying isocyanate functions. In these two cases, the alcohol functionsare polymerisable groups, as these functions are involved in thepolymerisation reactions.

As non-limiting examples, the monomer could be prepared for example bycoupling of a reagent carrying one or two polymerisable functionalgroup(s) GFP₂ and a halogen with another reagent carrying a boronicester function and an alcohol function, according to methods known tothe person skilled in the art. This monomer could also be prepared forexample by coupling of a reagent carrying one or two polymerisablefunctional group(s) GFP₂ and a halogen with another reagent carrying aboronic ester function and a carboxylic acid function, according tomethods known to the person skilled in the art.

This monomer could also be prepared for example by coupling of a reagentcarrying one or two polymerisable functional group(s) GFP₂ and ananhydride function with another reagent carrying a boronic esterfunction and an alcohol function, according to methods known to theperson skilled in the art. This monomer could also be prepared forexample by coupling of a reagent carrying one or two polymerisablefunctional group(s) GFP₂ and an anhydride function with another reagentcarrying a boronic ester function and a primary amine function,according to methods known to the person skilled in the art.

This monomer could also be prepared for example by coupling of a reagentcarrying one or two polymerisable functional group(s) GFP₂ and acarboxylic acid or acyl halide function with another reagent carrying aboronic ester function and an alcohol function, according to methodsknown to the person skilled in the art. This monomer could also beprepared for example by coupling of a reagent carrying one or twopolymerisable functional group(s) GFP₂ and a carboxylic acid or acylhalide function with another reagent carrying a boronic ester functionand a primary amine function, according to methods known to the personskilled in the art.

This monomer could also be prepared for example by coupling of a reagentcarrying one or two polymerisable functional group(s) GFP₂ and analcohol function with another reagent carrying a boronic ester functionand a carboxylic acid or ester function, according to methods known tothe person skilled in the art. This monomer could also be prepared forexample by coupling of a reagent carrying one or two polymerisablefunctional group(s) GFP₂ and a primary amine function with anotherreagent carrying a boronic ester function and a carboxylic acid or esterfunction, according to methods known to the person skilled in the art.

This monomer could also be prepared for example by coupling of a reagentcarrying one or two polymerisable functional group(s) GFP₂ and an aminefunction with another reagent carrying a boronic ester function and anacrylate function, according to methods known to the person skilled inthe art.

This monomer could also be prepared for example by coupling of a reagentcarrying one or two polymerisable functional group(s) GFP₂ and anisocyanate function with another reagent carrying a boronic esterfunction and an alcohol function, according to methods known to theperson skilled in the art.

These initial reagents are commercially available or may be synthesisedaccording to methods known to the person skilled in the art.

Cross-Linking Agent (b):

As for the additive previously described, to enable the formation of across-linked polymer network with exchangeable pending links andcross-links, a cross-linking agent that will not, on its own, react withitself and lose its functionality, is preferably used. In this way, thecross-linking agent carries the following pending and/or terminalfunctions:

-   -   boronic ester functions linked by at least one carbon atom of        the dioxaborolane or dioxaborinane ring; or    -   boronic ester functions linked by the boron atom of the        dioxaborolane or dioxaborinane ring.

A first usable cross-linking agent is a compound comprising at least twoboronic ester functions.

This first cross-linking agent is called a “bi- or multifunctionalcross-linking agent”.

The cross-linking agent may also be a monomer or a polymer.

In all these cases, the boron atom of the boronic ester function islinked by a covalent bond through a carbon atom to a hydrocarbonradical.

In a first embodiment, the cross-linking agent is a compound comprisingat least two boronic ester functions.

This compound may or may not include a functional group that ispolymerisable by the mode of polymerisation of monomers put into play.

The cross-linking agent is preferably a compound of formula (Ia) or (Ib)as described above.

In a particular embodiment, at least one of the radicals {R₁, R′₁, R″₁}and at least one of the radicals {R_(3i), R′_(3i), R″_(3i)} carries atleast one functional group that is polymerisable by the mode ofpolymerisation of monomers put into play or the radical R₆ and at leastone of the radicals R_(8i) carry at least one functional grouppolymerisable by the mode of polymerisation of monomers put into play.

The polymerisable functional group is preferably a functional group thatis polymerisable by radical polymerisation, by polymerisation bycoordination, by ring-opening polymerisation, by polyaddition or bypolycondensation. As examples, alcohol, epoxide, carboxylic acid, ester,primary or secondary amine, isocyanate or vinylic functions may bementioned.

Preferably, when none of the radicals in formula (Ia) or (Ib) carries apolymerisable functional group, then:

-   -   When the boronic ester function in monomer (a) is linked by at        least one carbon atom of the dioxaborolane or dioxaborinane ring        to the polymerisable group, preferably a compound of formula        (IIb), then the cross-linking agent is the compound of formula        (Ia);    -   When the boronic ester function in monomer (a) is linked by the        boron atom of the dioxaborolane or dioxaborinane ring,        preferably a compound of formula (IIa), then the cross-linking        agent is the compound of formula (Ib).

In a second embodiment, the cross-linking agent is a polymer.

In this second embodiment, the polymer includes pending boronic estergroups. The polymer carries:

-   -   pending boronic ester functional groups of formula (EB1) or        (EB2), not containing polymerisable groups, linked to the        polymer by at least one carbon atom of the dioxaborolane or        dioxaborinane ring; or    -   pending boronic ester functional groups of formula (EB1) or        (EB2), not containing polymerisable groups, linked to the        polymer by the boron atom of the dioxaborolane or dioxaborinane        ring.

The polymeric chain may be any polymer that may be functionalised withpending boronic ester groups.

The use of a polymer as cross-linking agent enables the viscosity of thecomposition of monomers to be polymerised to be modulated.

The choice of nature of the atom through which the pending boronic esterfunctional groups are linked to the polymer will depend on the nature ofthe atom through which the pending boronic ester functional groups arelinked to the polymerisable group of monomer (a).

In this way, when the pending boronic ester groups in monomer (a) arelinked to the polymerisable group by at least one carbon atom of thedioxaborolane or dioxaborinane ring, preferably a compound of formula(IIb), a polymer containing pending boronic ester functional groupslinked to the polymer by the boron atom of the dioxaborolane ordioxaborinane ring is chosen as the polymer.

In this way, when the pending boronic ester groups in monomer (a) arelinked to the polymerisable group by the boron atom of the dioxaborolaneor dioxaborinane ring, preferably a compound of formula (IIa), a polymercontaining pending boronic ester functional groups linked to the polymerby at least one carbon atom of the dioxaborolane or dioxaborinane ringis chosen as the polymer.

In a third embodiment, the cross-linking agent is a monomer that is aboronic ester functional compound, precursor to a thermoplastic polymeror thermoset, comprising at least one boronic ester function per monomerand carrying at least one polymerisable group This monomer canhereinafter be referred to as “monomer (b)”.

Monomer (b) preferably includes only one or two polymerisable groups. Inparticular:

-   -   monomer (b) includes a single polymerisable group when the group        is polymerisable by radical polymerisation, by polymerisation by        coordination, or by ring-opening polymerisation    -   monomer (b) includes only two polymerisable groups when the        groups are polymerisable by polyaddition or by polycondensation.

In a first embodiment, the monomer (b) is preferably of formula (IIIa),(IIIb1) or (IIIb2) below:

In whichR₃₁, R′₃₁, R″₃₁, R₃₅, R″₃₅, identical or different, each represent,independently of one another, a hydrogen atom or a hydrocarbon groupR₃₆ represents a hydrocarbon groupR₃₂ and R₃₄, identical or different, each represent a hydrocarbon groupR₃₂ is linked to the boronic ester function by a covalent bond through acarbon atom{R₃₁, R₃₅, R″₃₅} can together form, in pairs, an aliphatic or aromaticring{R₃₄, R₃₅, R″₃₅} can together form, in pairs, an aliphatic or aromaticringR₃₆ is linked to the boron atom by a covalent bond through a carbon atomR₃₂ and R₃₄, identical or different, are each preferably an aliphatic,aromatic, arylaliphatic or cycloaliphatic group that may also containheteroatoms such as O, N, S, or Si. In a preferred embodiment, R₃₂ andR₃₄, identical or different, each represent an aromatic orheteroaromatic group.k equals 0 or 1GFP₃ represents a polymerisable functional group as describedpreviously.m₃ equals 1 or 2.

Hereinafter, the terms (IIIb) designate either the formula (IIIb1) orthe formula (IIIb2).

Preferably, m₃ equals 2 when GFP₃ is polymerisable by polyaddition or bypolycondensation. Preferably, m₃ equals 1 when GFP₃ is polymerisable byradical polymerisation, by polymerisation by coordination, or byring-opening polymerisation.

None of the radicals R₃₁, R′₃₁, R″₃₁, R₃₅, R″₃₅, or R₃₆ carries afunctional group that is polymerisable by the mode of polymerisationused to polymerise GFP₃.

Apart from GFP₃, R₃₂ and R₃₄, do not carry any other functional groupthat is polymerisable by the mode of polymerisation used to polymeriseGFP₃.

R₃₂ and R₃₄, identical or different, can in particular represent a ring,hence allowing the presence of several blocks [boronic ester], possiblyon each carbon atom of the ring or a hydrocarbon chain enabling thepresence of several blocks [boronic ester], possibly on different carbonatoms of the chain.

R₃₂ and R₃₄, identical or different, are each preferably an aliphatic,aromatic, arylaliphatic or cycloaliphatic group that may also containheteroatoms such as O, N, S, or Si. In a preferred embodiment, R₃₂ andR₃₄, identical or different, each represent an aromatic orheteroaromatic group.

Preferably, R₃₂ and R₃₄, identical or different, each represent a C₁-C₁₂alkanediyl group, a benzene ring, a naphthalene ring, an arylaliphaticgroup comprising two benzene rings linked by a C₁-C₆ alkanediyl group, apyrimidine ring or a triazine ring.

In particular, the radical R₃₂ or R₃₄ can contain heteroatoms, inparticular chosen from among O, N, S or Si, and/or may be substituted.In particular, this radical Ry may be substituted by functional groupssuch as ester or amide functions, on condition that these functionalgroups are not involved in the polymerisation reactions. In particular,this radical is substituted by a halogen, an -Rz, —OH, —NHRz, —NRzR′z,—C(O)—OH, —C(O)—NRzR′z, —C(O)—O-Rz, —O—C(O)-Rz, —O—C(O)—O-Rz,—O—C(O)—N(H)-Rz, —N(H)—C(O)—O-Rz, —O-Rz, —S-Rz, —C(O)—N(H)-Rz,—N(H)—C(O)-Rz group with Rz, R′z, identical or different, representing aC₁-C₅₀ alkyl radical, insofar as this group is not involved in thepolymerisation reactions. In particular, this radical may include ester,amide, ether, thioether, secondary or tertiary amine, carbonate,urethane, carbamide or anhydride functions.

R₃₁, R′₃₁, R″₃₁, R₃₅, R′₃₅, identical or different, preferably representa hydrogen atom or an alkyl, alkenyl, aryl, cycloalkyl, heteroaryl,heteroalkyl or heterocycloalkyl group, and each of these groups may besubstituted, or R₃₁, R′₃₁, R″₃₁, or R₃₄, R₃₅, R″₃₅, together form, inpairs, an aliphatic or aromatic ring.

In a second embodiment, monomer (b) is a compound containing a boronicester function the boron atom of which is linked to at least onepolymerisable group and in which at least one carbon atom of the boronicester ring is linked to at least one polymerisable group; said groupsbeing polymerisable by the same mechanism as that used to polymerisemonomer (a).

When the polymerisation is of the polyaddition/polycondensation type,monomer (b) is a compound containing a boronic ester function the boronatom of which is linked to two polymerisable groups and in which atleast one carbon atom of the boronic ester ring is linked to twopolymerisable groups. In other types of polymerisation, monomer (b) is acompound containing a boronic ester function the boron atom of which islinked to one polymerisable group and in which at least one carbon atomof the boronic ester ring is linked to one polymerisable group.

Preferably, monomer (b) has the formula (IVa) or (IVb) below:

-   -   in which    -   R₄₁, R′₄₁, R″₄₁, R₄₅, R″₄₅, identical or different, each        represent, independently of one another, a hydrogen atom or a        hydrocarbon group    -   R₄₆ represents a hydrocarbon group    -   R₄₂, R′₄₂ and R₄₄, identical or different, each represent a        hydrocarbon group R₄₂ and R₄₆ are each linked to the boronic        ester function by a covalent bond through a carbon atom    -   {R₄₁, R″₄₁, R′₄₂} can together form, in pairs, an aliphatic or        aromatic ring    -   {R₄₄, R₄₅, R″₄₅} can together form, in pairs, an aliphatic or        aromatic ring    -   R′₄₂, R₄₂, R₄₄ and R₄₆, identical or different, are each        preferably an aliphatic, aromatic, arylaliphatic or        cycloaliphatic group that may also contain heteroatoms such as        O, N, S, or Si. In a preferred embodiment, R′₄₂, R₄₂, R₄₄ and        R₄₆, identical or different, each represent an aromatic or        heteroaromatic group    -   k equals 0 or 1    -   GFP₄ and GFP′₄ identical or different, each represents a        polymerisable functional group as described previously.    -   m₄ equals 1 or 2.

Hereinafter, the terms (IV) designate either the formula (IVa) or theformula (IVb).

Preferably, m₄ equals 2 when GFP₄ and GFP′₄ are polymerisable bypolyaddition or by polycondensation. Preferably, m₄ equals 1 when GFP₄and GFP′₄ are polymerisable by radical polymerisation, by polymerisationby coordination, or by ring-opening polymerisation.

R₄₂ et R₄₄, R′₄₂ and R₄₅, identical or different, are each preferably analiphatic, aromatic, arylaliphatic or cycloaliphatic group that may alsocontain heteroatoms such as O, N, S, or Si. In a preferred embodiment,R₄₂ and R₄₄ identical or different, each represent an aromatic orheteroaromatic group.

Preferably, R₄₂ and R₄₄, R′₄₂ and R₄₆, identical or different, eachrepresent a C₁-C₁₂ alkanediyl group, a benzene ring, a naphthalene ring,an arylaliphatic group comprising two benzene rings linked by a C₁-C₆alkanediyl group, a pyrimidine ring or a triazine ring.

In particular, the radical R₄₂ or R₄₄, R′₄₂ or R₄₆ can containheteroatoms, in particular chosen from among O, N, S or Si, and/or maybe substituted. In particular, this radical Ry may be substituted byfunctional groups such as ester or amide functions, on condition thatthese functional groups are not involved in the polymerisationreactions. In particular, this radical is substituted by a halogen, an-Rz, —OH, —NHRz, —NRzR′z, —C(O)—OH, —C(O)—NRzR′z, —C(O)—O-Rz,—O—C(O)-Rz, —O—C(O)—O-Rz, —O—C(O)—N(H)-Rz, —N(H)—C(O)—O-Rz, —O-Rz,—S-Rz, —C(O)—N(H)-Rz, —N(H)—C(O)-Rz group with Rz, R′z, identical ordifferent, representing a C₁-C₅₀ alkyl radical, insofar as this group isnot involved in the polymerisation reactions. In particular, thisradical may include ester, amide, ether, thioether, secondary ortertiary amine, carbonate, urethane, carbamide or anhydride functions.R₄₁, R″₄₁, R₄₅, R″₄₅, identical or different, preferably represent ahydrogen atom or an alkyl, alkenyl, aryl, cycloalkyl, heteroaryl,heteroalkyl or heterocycloalkyl group, and each of these groups may besubstituted, or R₄, R″₄₁, R′₄₂ or R₄₄, R₄₅, R″₄₅, together form, inpairs, an aliphatic or aromatic ring.

In one or other of these embodiments, the polymerisable functional groupis preferably a functional group that is polymerisable by radicalpolymerisation, by polymerisation by coordination, by ring-openingpolymerisation, by polyaddition or by polycondensation. As examples,alcohol, epoxide, carboxylic acid, ester, primary or secondary amine,isocyanate or vinylic functions may be mentioned.

In particular, when the polymerisation is conducted in the presence ofmonomers (a) in which the boronic ester function is linked to thepolymerisable group by the boron atom of the dioxaborolane ordioxaborinane ring, preferably of formula (IIa), and of monomers (b) inwhich the boronic ester function is linked to the polymerisable group byat least one carbon atom of the dioxaborolane or dioxaborinane ring,preferably of formula (IIIb), and respectively in the presence ofmonomers (a) in which the boronic ester function is linked to thepolymerisable group by at least one carbon atom of the dioxaborolane ordioxaborinane ring, preferably of formula (IIb), and of monomers (b) inwhich the boronic ester function is linked to the polymerisable group bythe boron atom of the dioxaborolane or dioxaborinane ring, preferably offormula (IIIa), a cross-linked polymer presenting the desiredthermosetting/thermoplastic properties may be obtained. Specifically,the polymer network will contain pending boronic ester functionalisedgroups, of small size (i.e. that do not form part of the main chain ofthe polymer), available for exchange reactions. In such a case, thepresence of a bi- or multifunctional means of cross-linking, for exampleof formula (Ia) or (Ib), is optional.

In particular, when the polymerisation is conducted in the presence ofmonomers (a) in which the boronic ester function is linked to thepolymerisable group by the boron atom or by at least one carbon atom ofthe dioxaborolane or dioxaborinane ring, preferably of formula (IIa) or(IIb), and of monomers (b) of formula (IV), a cross-linked polymerpresenting the desired thermosetting/thermoplastic properties may beobtained. Specifically, the polymer network will contain pending boronicester functionalised groups, of small size (i.e. that do not form partof the main chain of the polymer), available for exchange reactions. Insuch a case, the presence of a bi- or multifunctional means ofcross-linking, for example of formula (Ia) or (Ib), is optional.

The cross-linking agent of the first, second and third embodiments maybe used in combination, in particular as pairs, or all three together.

They may be synthesised by known methods, notably by those described forthe preparation of monomers (a).

The copolymerisation is preferably carried out in the presence ofmonomers (c) that are precursors to thermoplastic polymers that do notinclude a boronic ester group. These monomers are commerciallyavailable.

Monomer (c) preferably includes only one or two polymerisable groups. Inparticular:

-   -   monomer (c) includes a single polymerisable group when the group        is polymerisable by radical polymerisation, by polymerisation by        coordination, or by ring-opening polymerisation    -   monomer (c) includes only two polymerisable groups when the        groups are polymerisable by polyaddition or by polycondensation.

By the process according to the invention, polymer preparations havingthe properties of thermosets and thermoplastics may be prepared from anythermoplastic polymer precursor.

For example, the polymer precursor of interest is chosen from the groupcomprising styrene and its derivatives, alkyl methacrylates, arylalkylmethacrylates, alkyl acrylates, arylalkyl acrylates, acrylonitrile,acrylamides, methacrylamides, ethylene, fluoroalkyl methacrylates,fluoroalkyl acrylates, halogenated alkenes (tetrafluoroethylene,chlorotrifluoroethylene), alkyl dienes (butadiene, isoprene), vinylacetate, vinyl chloride, vinylidene fluoride, maleic anhydride,maleimides, N-vinylpyrrolidone, 2-vinylpyridine, 4-vinylpyridine,N-vinylcarbazole and appropriate mixtures. “Appropriate mixtures”designates precursors that are compatible to be copolymerised. This mayeasily be determined by the person skilled in the art on the basis ofhis/her general knowledge.

In another example, the polymer precursor of interest is chosen from thegroup comprising polyols, in particular di-alcohols, primary orsecondary polyamines, in particular diamines, dicarboxylic acids,diesters, di- or triepoxides and diisocyanates.

In another example, the polymer precursor of interest is chosen from thegroup comprising lactones and lactams.

In another example, the polymer precursor of interest is chosen from thegroup of cyclic alkenes, such as norbornene or cyclooctene.

In another example, the polymer precursor of interest is chosen from thegroup of olefins, such as ethylene or propylene.

These monomers are commercially available.

It is perfectly conceivable to use several different monomers precursorof polymers of interest.

The person skilled in the art knows how to choose compatible monomers.

The polymer of the invention may be prepared by polymerisation:

-   -   of monomers (c)    -   of monomers (a), preferably of formula (IIa) or (IIb)    -   of a cross-linking agent as defined previously, in particular a        compound of formula (Ia) or (Ib) or a monomer (b), preferably of        formula (IIIa) or (IIIb) or of formula (IV).

The nature of the compound of formula (I) or (III), and so the choicebetween the formulas (Ia) or (Ib)/(IIIa) or (IIIb) will depend on themonomer (a) chosen. In this way, preferably, when this monomer is acompound of formula (IIa), the cross-linking agent is of formula (Ib) or(IIIb); and respectively when this monomer is a compound of formula(IIb), the cross-linking agent is of formula (Ia) or (IIIa) The monomerof formula (IV) may be used with any monomer (a).

When the polymerisation is carried out in the presence of thesecompounds, a cross-linked polymer showing the desiredthermosetting/thermoplastic properties may be obtained. The polymernetwork will contain pending boronic ester functionalised groups offormula (EB1) or (EB2), of small size (i.e. that do not form part of themain chain of the polymer), available for exchange reactions.

The polymers according to the invention include pending boronic esterfunctions of formula (EB1) or (EB2). The polymers of the invention alsoinclude boronic ester functions of formula (EB1) or (EB2) in theirside-chains forming cross-links. This enables an exchange betweenboronic esters and improves the cross-linking of the polymers. Theinventors think that the exchange reactions between boronic estersenables a circulation of cross-links and could explain the thermoplasticbehaviour when the composition, in itself, is insoluble like athermoset.

The number and position of the cross-links will vary depending on thecompounds used and the relative concentrations of these compounds. Forexample, the polymer could contain one cross-link for every 1000 monomerunits. The number of cross-links in the polymers of the invention mayvary from one cross-link for every 5000 units to one cross-link forevery 3 units, preferably from one cross-link for every 2000 units toone cross-link for every 6 units, more preferably from one cross-linkfor every 1000 units to one cross-link for every 20 units, still morepreferably from one cross-link for every 500 units to one cross-link forevery 80 units.

In the invention, the molar ratio [monomer (c)]:[monomer (a)+compound offormula (Ia) or (Ib)] is preferably between 0.01 and 500, morepreferably between 0.1 and 100, still more preferably between 1 and 50.

The molar ratio [monomer (c)]:[monomer (a)+monomer (b)] is preferablybetween 0.01 and 500, more preferably between 0.1 and 100, still morepreferably between 1 and 50.

The molar ratio [compound of formula (Ia) or (Ib)]:[monomer (a)] ispreferably between 5 and 0.001, more preferably between 1 and 0.005 andstill more preferably between 0.5 and 0.01.

The molar ratio [monomer (a)]:[monomer (b)] is preferably between 500and 0.002, more preferably between 100 and 0.01 and still morepreferably between 40 and 0.025.

Some examples of networks that may be obtained according to theinvention will be described. In the case in which the primary aminefunction can react with two other functions, the primary amine functionis equivalent to two polymerisable groups.

The invention enables the preparation of epoxy networks.

These epoxy networks may be obtained by copolymerisation:

-   -   of diepoxide, bis(secondary amine) or primary amine monomers        (a);    -   with one or more cross-linking agent as defined previously, in        particular        -   one or more compounds of formula (Ia) or (Ib), which may or            may not contain polymerisable groups;        -   monomers of formula (IIIa) or (IIIb) and/or of formula (IV)            that are chosen among diepoxide, bis(secondary amine) or            primary amine compounds    -   preferably also in the presence of one or more diepoxide or        bis(secondary amine) monomers (c), more particularly in the        presence of diepoxide monomers (c) and bis(secondary amine)        monomers (c)    -   if applicable in the presence of cross-linking agents usually        used to form epoxy resins, that is polyamines or polyepoxides        that do not include any boronic ester function of formula (EB1)        or (EB2).

In an example embodiment, the epoxy networks may be obtained bycopolymerisation:

-   -   of diepoxide, bis(secondary amine) or primary amine monomers        (a);    -   of compounds of formula (Ia) or (Ib) comprising terminal epoxide        groups    -   and/or of compounds of formula (Ia) or (Ib) comprising terminal        primary or secondary amine groups    -   if applicable, of primary or secondary diamine or triamine        monomers (c)    -   if applicable, of diepoxide or triepoxide monomers (c)    -   if applicable in the presence of cross-linking agents usually        used to form epoxy resins, that is polyamines or polyepoxides        that do not include any boronic ester function of formula (EB1)        or (EB2).

In another example embodiment, the epoxy networks may be obtained bycopolymerisation:

-   -   of secondary diamine or triamine or primary amine monomers (c)    -   of diepoxide or triepoxide monomers (c)    -   of diepoxide, bis(secondary amine) or primary amine monomers (a)    -   of diepoxide, bis(secondary amine) or primary amine monomers        (b), in particular of formula (IIIa) or (IIIb) and/or of formula        (IV), and/or compound of formula (Ia) or (Ib)    -   if applicable in the presence of cross-linking agents usually        used to form epoxy resins, that is polyamines or polyepoxides        that do not include any boronic ester function of formula (EB1)        or (EB2).

In this way, it is possible, starting from monomers usually used for themanufacture of epoxy resins, and by adding a compatible monomer (a)according to the invention and compatible cross-linking agent asdefined, to prepare epoxy networks containing pending links andcross-links that are exchangeable by boronic ester metathesis reactions.

The invention enables the preparation of polyurethane networks.

These polyurethane networks may be obtained by copolymerisation:

-   -   of di-alcohol monomers (a);    -   of di-isocyanate monomers (c);    -   with one or more cross-linking agent as defined previously, in        particular        -   one or more compounds of formula (Ia) or (Ib), which may or            may not contain polymerisable groups;        -   monomers of formula (IIIa) or (IIIb) that are chosen among            di-isocyanate or di-alcohol compounds        -   monomers of formula (IV) that are chosen among            tetra-alcohols    -   preferably in the presence of one or more di-alcohol monomers        (c)    -   if applicable in the presence of cross-linking agents usually        used to form polyurethane resins, that is polyols that do not        include any boronic ester function of formula (EB1) or (EB2).

In an example embodiment, the polyurethane networks may be obtained bycopolymerisation:

-   -   of di-alcohol monomers (a);    -   of compounds of formula (Ia) or (Ib) comprising terminal        hydroxyl groups    -   of di-isocyanate monomers (c)    -   if applicable, of di-alcohol monomers (c)    -   if applicable in the presence of cross-linking agents usually        used to form polyurethane resins, that is polyols that do not        include any boronic ester function of formula (EB1) or (EB2).

In another example embodiment, the polyurethane networks may be obtainedby copolymerisation:

-   -   of di-alcohol monomers (c)    -   of di-isocyanate monomers (c)    -   of di-alcohol monomers (a)    -   of a diol monomer (b) and/or a compound of formula (Ia) or (Ib)        and/or monomers of formula (IV) chosen from among the        tetra-alcohols.

In this way, it is possible, starting from monomers usually used for themanufacture of polyurethane resins, and by adding a compatible monomer(a) according to the invention and compatible cross-linking agent asdefined, to prepare polyurethane networks containing pending links andcross-links that are exchangeable by boronic ester metathesis reactions.

The invention enables the preparation of polyamide networks.

These polyamide networks may be obtained by copolymerisation:

-   -   of primary diamine or diester or dicarboxylic acid monomers (a);    -   of diester or dicarboxylic acid monomers (c);    -   of primary diamine monomers (c)    -   if applicable, of primary triamine or triester or tricarboxylic        acid monomers (c)    -   with one or more cross-linking agent as defined previously, in        particular        -   one or more compounds of formula (Ia) or (Ib), which may or            may not contain polymerisable groups;        -   monomers of formula (IIIa) or (IIIb) that are chosen among            primary diamine, diester or dicarboxylic acid compounds        -   monomers of formula (IV) that are chosen among primary            tetramines, or tetraesters or tetracarboxylic acids

In an example embodiment, the polyamide networks may be obtained bycopolymerisation:

-   -   of primary diamine monomers (c)    -   of diester monomers (c)    -   of primary diamine or diester monomers (a)    -   of a primary diamine or diester monomer (b) and/or compound of        formula (Ia) or (Ib) and/or monomers (b) of formula (IV) that        are chosen among primary tetramines, or tetraesters    -   if applicable, of primary triamine or triester monomers (c)

In another example embodiment, the polyamide networks may be obtained bycopolymerisation:

-   -   of primary diamine monomers (c)    -   of dicarboxylic acid monomers (c)    -   of diamine or dicarboxylic acid monomers (a)    -   of a primary diamine or dicarboxylic acid monomer (b) and/or        compound of formula (Ia) or (Ib) and/or monomers (b) of        formula (IV) that are chosen among primary tetramines, or        tetracarboxylic acids    -   if applicable, of primary triamine or tricarboxylic acid        monomers (c)

In this way, it is possible, starting from monomers usually used for themanufacture of polyamide resins, and by adding a compatible monomer (a)according to the invention and compatible cross-linking agent asdefined, to prepare polyamide networks containing pending links andcross-links that are exchangeable by boronic ester metathesis reactions.

The invention enables the preparation of polyester networks.

These polyester networks may be obtained by copolymerisation:

-   -   of di-alcohol or diester monomers (a);    -   of diester monomers (c);    -   of di-alcohol monomers (c)    -   if applicable, of tri-alcohol or tetra-alcohol or triester        monomers (c)    -   with one or more cross-linking agent as defined previously, in        particular        -   one or more compounds of formula (Ia) or (Ib), which may or            may not contain polymerisable groups;        -   monomers of formula (IIIa) or (IIIb) that are chosen among            di-alcohol or diester compounds        -   monomers of formula (IV) that are chosen among            tetra-alcohols or tetraesters

In an example embodiment, the polyester networks may be obtained bycopolymerisation:

-   -   of diol monomers (c)    -   of diester monomers (c)    -   of diol monomers (a)    -   of a di-alcohol or diester monomer (b) and/or compound of        formula (Ia) or (Ib) and/or monomers of formula (IV) that are        chosen among tetra-alcohols or tetraesters    -   if applicable, of tri-alcohol or tetra-alcohol monomers (c)

In another example embodiment, the polyester networks may be obtained bycopolymerisation:

-   -   of diol monomers (c)    -   of diester monomers (c)    -   of diester monomers (a)    -   of a di-alcohol or diester monomer (b) and/or compound of        formula (Ia) or (Ib) and/or monomers of formula (IV) that are        chosen among tetra-alcohols or tetraesters    -   if applicable, of tri-alcohol or tetra-alcohol monomers (c)

In this way, it is possible, starting from monomers usually used for themanufacture of polyester resins, and by adding a compatible monomer (a)according to the invention and compatible cross-linking agent asdefined, to prepare polyester networks containing pending links andcross-links that are exchangeable by boronic ester metathesis reactions.

The invention enables the preparation of vinylic networks.

These vinylic networks may be obtained by copolymerisation:

-   -   of vinylic monomers (a);    -   of vinylic monomers (c);    -   with one or more cross-linking agent as defined previously, in        particular        -   one or more compounds of formula (Ia) or (Ib), which may or            may not contain polymerisable groups;        -   monomers of formula (IIIa) or (IIIb) that are chosen among            vinylic compounds        -   monomers of formula (IV) that are chosen among divinylic            compounds    -   if applicable a conventional cross-linking agent, comprising        several vinylic bonds and not comprising any boronic ester        function of formula (EB1) or (EB2).

In this way, it is possible, starting from monomers usually used for themanufacture of vinylic resins, and by adding a compatible monomer (a)according to the invention and compatible cross-linking agent asdefined, to prepare vinylic networks containing pending links andcross-links that are exchangeable by boronic ester metathesis reactions.

The compositions obtained after copolymerisation may include freemonofunctional boronic esters, such as defined previously for thecompositions obtained by cross-linking of polymers.

The physical and chemical properties of the polymers of the inventiondepend strongly on the compounds used, in particular on the precursormonomers used.

Nevertheless, starting from a precursor monomer of a thermoplasticpolymer, all the polymers combine the properties of a thermoplasticpolymer with those of a thermoset. In particular, the polymer isinsoluble like a thermoset but may be recycled and/or reshaped at atemperature higher than the glass transition temperature or the meltingtemperature of the polymer, preferably higher than Tg or Tf+10° C., morepreferably higher than Tg or Tf+20° C., still more preferably higherthan Tg or Tf+40° C., still more preferably higher than Tg or Tf+80° C.,if the glass transition temperature or the melting temperature is lowerthan 25° C.

The number average molar mass, M_(n), of the linear or branched polymersobtained after degradation is preferably between 1500 g/mol and 2000000g/mol, more preferably between 5000 g/mol and 500000 g/mol and stillmore preferably between 15000 g/mol and 200000 g/mol.

The dispersity, 0=M_(w)/M_(n), of the linear or branched polymersobtained after degradation is preferably between 1.01 and 15, morepreferably between 1.10 and 10 and still more preferably between 1.5 and5.

These compositions include free molecules as defined previously for thecompositions obtained by cross-linking of a polymer.

Another object of the invention is a copolymerisation process accordingto the steps described previously.

The object of the invention is a copolymerisation process of thefollowing compounds:

-   -   (a) Precursor monomers to thermoplastic polymers comprising at        least one pending boronic ester group, said pending boronic        ester group not containing any polymerisable group;    -   (b) Cross-linking agent comprising at least one boronic ester        group enabling the formation of a network of cross-linked        polymer containing pending functions and cross-links that are        exchangeable by boronic ester metathesis reactions; said boronic        esters being chosen from among the following dioxaborolane and        dioxaborinane rings of formulas (EB1) and (EB2):

-   -   -   in which        -   Rx, Rw and Rv are identical or different and each represent            a hydrogen atom or a hydrocarbon radical or form together,            as a pair, an aliphatic or aromatic ring        -   Ry is a hydrocarbon radical linked to the boron atom of the            dioxaborolane or dioxaborinane ring by a covalent bond            through a carbon atom.

    -   (c) if applicable monomers that are precursors to thermoplastic        polymers that do not include a boronic ester group of formula        (EB1) or (EB2).

The compositions obtained by this process may or may not include freemolecules.

The operating conditions for carrying out the polymerisation correspondto the conditions usually used for the thermoplastic monomersconsidered.

3. Polymers and Compositions According to the Invention

The polymers and compositions according to the invention have theadvantage of showing thermosetting and thermoplastic properties. Inparticular, the compositions according to the invention have at leastone, more preferably several, still more preferably all, of thefollowing properties:

-   -   thermal stability    -   three-dimensional network, meaning that the polymer can be as        insoluble as a thermoset    -   polymer offcuts can be reused    -   reshaping at a temperature higher than the glass transition        temperature (Tg) or the melting temperature (Tf), preferably        higher than Tg or Tf+10° C., more preferably higher than Tg or        Tf+20° C., still more preferably higher than Tg or Tf+40° C.,        still more preferably higher than Tg or Tf+80° C., if the glass        transition temperature or the melting temperature is lower than        25° C.    -   once cooled, it does not flow more than the reference polymer    -   increase in chemical resistance    -   malleable at high temperature    -   possibility to reshape the polymer of the invention    -   ability to relax all or some of the stresses present in the        material    -   objects may be manufactured by injection from these compositions    -   objects may be manufactured by extrusion from these compositions    -   objects may be manufactured by pressure moulding from these        compositions    -   objects may be manufactured by thermoshaping from these        compositions    -   objects may be manufactured by solvent casting from these        compositions    -   objects manufactured with these compositions may be repaired    -   objects manufactured with these compositions may be welded    -   objects manufactured with these compositions may be recycled    -   degradable: degradation of the polymer leads to linear or        branched polymer chains that may be reused.

When they are immersed in a solvent, preferably a good solvent, thepolymers of the invention, preferably the cross-linked polymer networksof the invention, preferably show the remarkable property that they canbe injected, notably through a syringe. When they are in the form ofliquid formulations, the cross-linked polymer compositions according tothe invention, preferably compositions forming a network of cross-linkedlinear or branched polymers, preferably show the remarkable propertythat they can be injected, notably through a syringe. Depending on thedegree of cross-linking of the cross-linked linear or branched polymernetworks, the cross-linked polymer compositions according to theinvention, and likewise when immersed in a good solvent and depending ontheir degree of cross-linking, the cross-linked polymer networks of theinvention, are injectable, notably through a syringe, while forming anetwork of cross-linked polymers that, when swollen by solvent,preferably a solvent other than water, can support its own weight andwill not collapse on the scale of 30 seconds, preferably 1 minute, morepreferably 2 minutes, still more preferably 5 minutes, still morepreferably 10 minutes, still more preferably 30 minutes, still morepreferably 1 hour, still more preferably 2 hours, still more preferably4 hours, still more preferably 6 hours, still more preferably 8 hours,so more preferably 12 hours, still more preferably 1 day, withoutapplication of a strain.

When they are in the form of liquid formulations, preferably in asolvent other than water, the cross-linked linear or branched polymernetworks according to the invention preferably show the property ofself-agglomeration when they are left in contact.

When they are immersed in a solvent, preferably a good solvent, thecross-linked polymer networks of the invention, preferably show theproperty of aggregating together when they are left in contact.

The degree of cross-linking:

-   -   of the cross-linked polymer compositions according to the        invention, preferably the compositions in the form of liquid        formulations forming networks of cross-linked linear or branched        polymers; or    -   of the cross-linked polymers of the invention, preferably the        cross-linked polymer networks of the invention immersed in a        good solvent;    -   may be modulated by addition of free monofunctional boronic        esters of formula (EB1) or (EB2) and/or of compounds of formula        (Ia), and/or of compounds of formula (Ib), and/or of linear or        branched polymers P2. Such a modulation of the cross-linking        degree may enable the release of molecules and/or polymers in        the formulation containing the cross-linked polymer compositions        according to the invention. The following are among the        non-limiting examples of molecules or polymers that could be        released: active substances, proteins, nucleic acids, amino        acids, vitamins, flavours, catalysts, chemical reagents,        pigments or other additives. The modulation of the cross-linking        degree may be carried further to perform uncrosslinking.

The cross-linked polymers of the invention, preferably the cross-linkedpolymer networks of the invention, including assembled compositions ofthe invention, can be uncrosslinked, and thus recycled, by addition of acompound (small molecule or polymer) comprising a 1,3- or 1,2-diolfunction. The compound is preferably a monofunctional 1,3- or 1,2-diol,more preferably mono-substituted. The cross-linked polymers of theinvention, preferably the cross-linked polymer networks of theinvention, can be uncrosslinked, and thus recycled, using water underpressure, for example in an autoclave. The cross-linked polymers of theinvention, preferably the cross-linked polymer networks of theinvention, including assembled compositions of the invention, can beuncrosslinked, and thus recycled, by addition of a compound (smallmolecule or polymer) comprising a boronic ester function. Preferably,the boronic ester function is derived from 1,2- or 1,3-diol. Thecompound is preferably a monofunctional boronic ester, more preferablymono-substituted.

When the modulation of the cross-linking degree is carried out toperform uncrosslinking of the cross-linked polymers of the invention,preferably of the cross-linked polymer networks of the invention,including assembled compositions of the invention, the compound used tomodulate the cross-linking density, preferably a monofunctional boronicester, preferably water under pressure, for example in a autoclave,preferably a 1,3- or 1,2-diol, is used in large excess as compared tothe boronic ester cross-links present in the cross-linked polymers ofthe invention, preferably of the cross-linked polymer networks of theinvention, including assembled compositions of the invention. By largeexcess, it should be understood that the molar ratio of [compound usedto modulate the cross-linking density in order to performuncrosslinking]/[cross-links containing boronic ester functions] ispreferably greater than 50, more preferably greater than 100, morepreferably greater than 150, more preferably greater than 200, morepreferably greater than 500, and still more preferably greater than1000.

The composition according to the invention can also include loads and/orfillers and/or additives. The loads and/or fillers and/or additives arein particular those normally used by the person skilled in the art.

Furthermore, the composition can include, in the mixture or in thenetwork, (an)other compatible polymer(s). The person skilled in the artknows how to choose such a polymer.

The polymer network compositions comprising at least one polymer networkwhose composition has been described above may also include: one or morepolymers, pigments, colourants, blueing agents, fillers, plastifiers,impact modifiers, fibres, flame retardants, antioxidants, lubricants,wood, glass and metal.

Among the polymers that can be mixed with the compositions all polymernetworks of the invention, examples include elastomers, thermosets,thermoplastic elastomers and impact-resistant polymers.

The term “pigments” designates coloured particles that are insoluble incomposition or in the polymer network among the pigments that may be theinvention, titanium dioxide, carbon black, carbon nanotubes, metallicparticles, silica, metal oxides, metallic sulfites or any other mineralpigments may be cited. Other pigments that may be mentioned arephthalocyanines, anthraquinones, quinacridones, dioxazines, azo dyes orany other organic pigment and natural pigments (madder, indigo, rosemadder, carmine, etc.) and pigment mixtures. The pigments can representbetween 0.05% and 70% of the composition of the formulation.

The term “colourants” designates molecules that are soluble in thecomposition all the polymer network and have the ability to absorb allor some of the visible light rays.

The term “blueing agent” designates a molecule that absorbs ultravioletlight rays and then re-emits this energy by fluorescence in the visiblespectrum. Blueing agents are notably used to give a certain whiteness.

Examples of fillers that may be used in the compositions or polymernetworks of the invention are: silica, clays, calcium carbonate, carbonblack and kaolins.

Examples of fibres that may be used in the compositions or polymernetworks of the invention are: glass fibre, carbon fibre, polyesterfibre, polyamide fibre, aramide fibre, polyethylene fibre, cellulosefibre and nano-cellulose. Organic fibres (linen, hemp, sisal, bamboo,etc.) may also be envisaged.

The fact that thermally conducting pigments, colourants or fibres may bepresent in the compositions or polymer networks of the invention may beused to facilitate the heating of an object of obtained from thecompositions or polymer networks of the invention and so to enable themanufacture, transformation recycling of an article obtained from thesecompositions or polymer networks of the invention as described below. Asnon-limiting examples of thermally conducting pigments, fibres orfillers, the following may be given: aluminium nitride (AlN), boronnitride (BN), MgSiN2, silicon carbide (SiC), graphite, graphene, carbonnanotubes, carbon fibres, metallic powders and stared combinations.

The presence in the compositions or polymer networks of the invention ofpigments, colourants or fibres capable of absorbing radiation may beused to ensure the heating of an article obtained from thesecompositions or polymer networks of the invention by means of aradiation source, for example a laser. The presence in the compositionsor polymer networks of the invention of electrically conducting pigmentsfibres or fillers such as carbon black, carbon nanotubes, carbon fibres,metallic powders, or magnetic particles, may be used to ensure theheating of an article obtained from these compositions or polymernetworks of the invention by the Joule effect or by microwaves. Suchheating procedures may enable the manufacture, transformation orrecycling of an article obtained from the compositions or polymernetworks of the invention as described below. Electrically conductingloads also enable electrostatic charges to be evacuated from thematerial or enable electrostatic painting

Another object of the invention is a process for preparation of thecompositions according to the invention. This process preferablyincludes the following steps:

-   -   Choosing a linear or branched polymer P1 with side-groups        carrying:        -   boronic ester functional groups of formula (EB1) or (EB2)            linked to the polymer by at least one carbon atom of the            dioxaborolane or dioxaborinane ring; or        -   boronic ester functional groups of formula (EB1) or (EB2)            linked to the polymer by the boron atom of the dioxaborolane            or dioxaborinane ring.    -   Choosing at least one additive carrying at least two boronic        ester groups of formula (EB1) or (EB2) that are capable of        reacting with the side groups of the polymer P1 to form a        cross-linked polymer composition, preferably a cross-linked        network, containing links and cross-links that are exchangeable        by boronic ester metathesis reactions.    -   mixing, in the molten state or in solution, said polymer P1 and        said additive to obtain the said composition.

The choice of substitutions and of the additive is made according to thedescription given above for compositions. A free monofunctional boronicester of formula (EB1) or (EB2) as described previously may be added.

The process may include a previous step to prepare polymer P1,comprising copolymerisation, for example by radical routes, bypolymerisation by coordination, by ring-opening polymerisation, bypolyaddition or by polycondensation, of a precursor monomer of P1 and amonomer carrying a boronic ester functional group of formula (EB1) or(EB2).

The process may include a previous step to prepare polymer P1,comprising grafting of pending boronic ester functions of formula (EB1)or (EB2) to a linear or branched polymer.

Another process according to the invention preferably includes thefollowing steps:

-   -   choosing at least one linear or branched polymer P1′ containing        functions enabling grafting,    -   choosing a combination of molecules of which the molecules        comprise at one end a functional group enabling covalent binding        of the molecule to the polymer P1′ and at the other end a        functional group chosen from among a boronic ester function of        formula (EB1) or (EB2) linked to the rest of the molecule by at        least one carbon atom of the dioxaborolane or dioxaborinane ring        (A), a boronic ester function of formula (EB1) or (EB2) linked        to the rest of the molecule by its boron atom of the        dioxaborolane or dioxaborinane ring (B), and/or molecules        comprising at two of their extremities functional groups        enabling covalent binding of the molecule to the polymer P1′ and        between these two extremities a boronic ester function of        formula (EB1) or (EB2) (C), the combination enabling grafting        and the creation of pending links and cross-links that are        exchangeable by boronic ester metathesis reactions.    -   mixing, in the molten state or in solution, said polymer P1′ and        said composition to obtain the said composition.

The choice of substitutions and of the composition is made according tothe description given above for compositions. A free monofunctionalboronic ester of formula (EB1) or (EB2) as described previously may beadded.

The process may include a previous step to prepare polymer P1′,comprising copolymerisation, for example by radical routes, bypolymerisation by coordination, by ring-opening polymerisation, bypolyaddition or by polycondensation, of a precursor monomer of P1′ and amonomer carrying a functional group enabling subsequent grafting ofboronic ester functions.

The process may include a previous step to prepare polymer P1′,comprising grafting of pending functions enabling grafting of boronicester functions to a linear or branched polymer.

Another object of the invention is a process for preparation of thecompositions according to the invention. This process includes thecopolymerisation of the monomers described under the conditionsappropriate to the polymerisable functional groups. The polymerisationis preferably a radical polymerisation, a polymerisation bycoordination, a ring-opening polymerisation, a polyaddition or apolycondensation.

Another object of the invention is a material obtained from thecomposition according to the invention.

Another object of the invention is a preparation process of a materialaccording to the invention, comprising the following steps:

-   -   Preparation of a composition according to the invention;    -   Shaping of the composition obtained therefrom.

The concept of shaping also includes the compounding of the compositionin the form of granules or powder, for example in the preparation offinished products. The shaping may also be carried out by processesknown to the person skilled in the art for the shaping of thermoplasticor thermosetting polymers. Notably, the processes of moulding,compression, injection, extrusion and thermoforming may be mentioned.Before having the form of the finished object, the material will usuallybe in the form of granules or powder.

Advantageously in the process according to the invention the preparationand forming steps may be concomitant. In particular, in the processesdescribed above, it is possible to functionalise and cross-link apolymer, for example by extrusion or injection during its shaping or ina compounding step.

Another object of the invention is a process for recycling a materialobtained comprising the following successive steps: a) reduction of thematerial to a powder by mechanical grinding; b) transformation of theparticles from step a) by applying a mechanical stress to the particlesat a temperature (T) higher than the glass transition temperature (Tg)or the melting temperature (Tf) of the polymer P1 or P1′, if applicableP2, preferably higher than Tg or Tf+10° C., more preferably higher thanTg or Tf+20° C., still more preferably higher than Tg or Tf+40° C.,still more preferably higher than Tg or Tf+80° C., if the glasstransition temperature or the melting temperature is lower than 25° C.

Another object of the invention is a formulation comprising acomposition according to the invention.

Another object of the invention is the use of an additive such asdefined above, or the combination such as defined above, in the presenceof a linear or branched polymer P1 or P1′ for the formation of acomposition comprising cross-linked polymers, preferably a cross-linkednetwork, containing pending links and cross-links that are exchangeableby boronic ester metathesis reactions. The nature of the additive or thecombination is chosen as a function of the polymer P1 or P1′, inparticular its functionalisation, according to the criteria detailedabove.

A free monofunctional boronic ester of formula (EB1) or (EB2) asdescribed previously may also be added to the composition.

Another object of the invention is a process to modify the rheology of acomposition, such as an oil or a paint, comprising the said polymer P1or P1′ by addition to the composition of an additive according to theinvention or a composition according to the invention. The rheology ismodified by choosing the concentration of the said additive orcomposition.

The nature of the additive or the combination is chosen as a function ofthe polymer P1 or P1′, in particular its functionalisation, according tothe criteria detailed above.

A free monofunctional boronic ester of formula (EB1) or (EB2) asdescribed previously may also be added to the composition.

Another object of the invention are combinations to cross-link linear orbranched polymers, preferably P1 or P1′, said combinations being chosenfrom among the combinations comprising:

-   -   A+B; A and B being as defined previously;    -   A and/or B+C; A, B and C being as defined previously;    -   A+compound of formula (Ia), as defined previously; or    -   B+compound of formula (Ib), as defined previously.

A, B and C are as defined previously.

These combinations can also include a free monofunctional boronic esterof formula (EB1) or (EB2).

EXAMPLES

The following examples illustrate the invention and are not limiting

The following examples illustrate the synthesis and the characterizationof boronic ester compounds

Example 1: General Procedure for the Synthesis of Boronic Esters, NMRCharacterizations

The boronic acid (1 eq.) and the diol (1.01 eq.) are mixed in diethylether (ca. 3 mL/1 mmol of the boronic acid). After five minutes, water(0.1 mL/3 mL Et₂O) is added. After complete dissolution of all reactantsmagnesium sulfate (0.5 g/3 mL Et₂O) is added gradually and the reactionmixture is stirred at room temperature for 24-76 hours. Then, thereaction mixture is filtered and concentrated under reduced pressure.The obtained product is introduced in heptane and the mixture is stirredat room temperature for ten minutes, filtered and concentrated underreduced pressure to yield the boronic ester as a white solid ortransparent oil.

3,5-Dimethylphenylboronic Acid 1,2-Propanediol Ester: MR 02-066

3,5-Dimethylphenylboronic Acid 1,2-Octanediol Ester: MR 02-067

3,5-Dimethylphenylboronic Acid 1,2-Dodecanediol Ester: MR 02-068

3,5-Bis(Trifluorométhyl)Phenylboronic Acid 1,2-Propanediol Ester: MR02-069

3,5-Bis(Trifluoromethyl)Phenylboronic Acid 1,2-Hexanediol Ester: MR02-070 Et MR 04-007

3,5-Bis(Trifluoromethyl)Phenylboronic Acid 1,2-Dodecanediol Ester: MR02-071

3,5-Dichlorophenylboronic Acid 1,2-Propanediol Ester: MR 02-072

3,5-Dichlorophenylboronic Acid 1,2-Hexanediol Ester: MR 02-073

3,5-Dichlorophenylboronic Acid 1,2-Dodecanediol Ester: MR 02-074

Phenylboronic Acid Pinacol Ester: MR 03-072

Cyclohexylboronic Acid 1,2-Propanediol Ester: MR 03-073

Propylboronic Acid 1,2-Dodecanediol Ester: MR 03-074

3,5-Bis(Trifluoromethyl)Phenylboronic Acid Pyrocatechol Ester: MR 03-079

Cyclohexylboronic Acid 1,2-Propanediol Ester: MR 03-081

Propylboronic Acid 1,2-Propanediol Ester: MR 03-082

3,5-Dichlorophenylboronic Acid Pyrocatechol Ester: MR 04-006

3,5-Dimethylphenylboronic Acid 1,3-Butanediol Ester: MR 04-012

4-Fluorophenylboronic Acid 1,2-Dodecanediol Ester: MR X-002

4-Fluorophenylboronic Acid 1,2-Propanediol Ester: MR X-010

Cyclohexylboronic Acid 1,3-Butanediol Ester: MR 04-014

Phenylboronic Acid 1,2-Propanediol Ester: MR 05-026

Phenylboronic Acid 1,2-Butananediol Ester: MR 2016a

3,5-Dimethylphenylboronic Acid 1,2-Butanediol Ester: MR 2016b

Phenylboronic Acid 1,3-Butanediol Ester: MR 05-033

Example 2: Kinetic Study of the Metathesis Reaction of Boronic Esters

The following experiments aim to evaluate the conditions (time,temperature, catalyst) under which boronic ester metathesis is observed.These examples allow to illustrate the influence of substituents linkedto the atoms of dioxaborolane or dioxaborinane rings, the size ofboronic ester rings, the temperature, the polarity of the reactionmedium, the presence of catalysts, on the reaction kinetics of boronicester metathesis.

A solution of a boronic ester MR-X (0.1 mmol per g of solvent) in theanhydrous solvent chosen for the reaction and a solution of a boronicester MR-Y (0.1 mmol per g of solvent) in the anhydrous solvent chosenfor the reaction are mixed. The resulting solution is stirred at a fixedtemperature and the evolution of the concentration of the differentcomponents of the mixture is monitored regularly by gas chromatography.

2.1 Metathesis Between Phenylboronic Esters

The examples were conducted in three solvents at 5° C.: anhydroushexane, anhydrous chloroform and anhydrous tetrahydrofuran.

The evolution of the molar percentage (ordinate; without unit) of thedifferent boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydrous hexane at5° C. is displayed in FIG. 4. It is observed that after 50 minutes themixture contains equimolar quantities of the compounds MR 02-066, MRX-002, MR 02-068, MR X-010.

The evolution of the molar percentage (ordinate; without unit) of thedifferent boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydrous chloroformat 5° C. is displayed in FIG. 5. It is observed that after 120 minutesthe mixture contains equimolar quantities of the compounds MR 02-066, MRX-002, MR 02-068, MR X-010.

The evolution of the molar percentage (ordinate; without unit) of thedifferent boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydroustetrahydrofuran at 5° C. is displayed in FIG. 6. It is observed thatafter 175 minutes the mixture contains equimolar quantities of thecompounds MR 02-066, MR X-002, MR 02-068, MR X-010.

2.2 Tests in Anhydrous Chloroform at 5° C. to Illustrate the Influenceof Substituents Attached to the Aromatic Ring of Phenylboronic Esters;Results to be Compared to Those of FIG. 5.

The evolution of the molar percentage (ordinate; without unit) of thedifferent boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydrous chloroformat 5° C. is displayed in FIG. 7.

2.3 Metathesis Between Phenylboronic Esters in Anhydrous Tetrahydrofuranat 5° C. in the Presence of Organic Catalysts; Results to be Compared toThose in FIG. 6.

Remark: the catalysts used, e.g. benzoic acid and triethylamine, areanhydrous.

The evolution of the molar percentage (ordinate; without unit) of thedifferent boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydroustetrahydrofuran at 5° C. in the presence of 1 mol % of anhydroustriethylamine is displayed in FIG. 8.

The evolution of the molar percentage (ordinate; without unit) of thedifferent boronic esters in time (abscissa; minutes) during themetathesis between the two phenylboronic esters in anhydroustetrahydrofuran at 5° C. in the presence of 1 mol % of anhydrous benzoicacid is displayed in FIG. 9.

2.4 Metathesis Between Alkylboronic Esters

The evolution of the molar percentage (ordinate; without unit) of thedifferent boronic esters in time (abscissa; minutes) during themetathesis between the two alkylboronic esters in anhydroustetrahydrofuran at room temperature is displayed in FIG. 10.

2.5 Metathesis Between Boronic Esters Containing Respectively anAryldiol Substituent and an Alkyldiol Substituent

The evolution of the molar percentage (ordinate; without unit) of thedifferent boronic esters in time (abscissa; minutes) during themetathesis between boronic esters containing respectively an aryldiolsubstituent and an alkyldiol substituent in anhydrous tetrahydrofuran atroom temperature is displayed in FIG. 11.

2.6 Metathesis Between Boronic Esters Containing Respectively a1,2-Alkydiol Substituent and a 1,3-Alkyldiol Substituent

The evolution of the molar percentage (ordinate; without unit) of thedifferent boronic esters in time (abscissa; minutes) during themetathesis between boronic esters containing respectively a1,2-alkyldiol substituent and a 1,3-alkyldiol substituent in anhydroustetrahydrofuran at room temperature is displayed in FIG. 12.

2.7 Metathesis Between Phenylboronic Esters in the Absence of Solventsand at Different Temperatures

The following examples illustrate the fact that the metathesis ofboronic esters can be conducted in bulk, i.e. in the absence ofsolvents, and in a large range of temperatures. The bulk metathesis ofboronic esters was conducted at three different temperatures: 60° C.,85° C. and 150° C.

General Procedure for the Metathesis Reaction of Boronic Esters in Bulkand Kinetic Study by Gas Chromatography (GC):

Equimolar quantities of MR-2016a and MR-02-066 were mixed in an ovendried and argon-purged Schlenk flask and the reaction mixtures were keptunder inert atmosphere and stirred at 60° C., respectively 85° C.,respectively 150° C.

GC analysis was conducted on a Shimadzu gas chromatograph GC-2014equipped with a Zebron-5HT “inferno” column and helium as carrier gas.Injection was done manually by injecting 1 μL sample volumes using a 10μL syringe from Hamilton (gastight 1701). Before running analysis theentire set-up was pre-heated to 350° C. and kept at constant carrier gasflow of 5 mL/min and split ratio of 2.0 for at least 30 minutes. Sampleswere analyzed with a flame ionization detector (FID). The following GCmethod was used to follow of the exchange reaction between boronicesters: T(injection/detector)=350° C., T(column)=120° C., T(ramp)=30°C./min, carrier gas flow 5.0 mL/min and split ratio=2.0. Samples weretaken with cleaned, dried and argon-purged needles and added to a smallvolume of dried DCM (dried, under argon) to dilute each sample mixturebefore injection.

The evolution of the molar percentage (ordinate; without unit) of thetwo starting boronic esters and of the two boronic esters formed duringthe metathesis reaction of phenylboronic esters MR-02-66 and MR-2016a inbulk at 85° C. is plotted as a function of time (abscissa; minutes) inFIG. 14.

The evolution of the molar percentage (ordinate; without unit) of thetwo starting boronic esters and of the two boronic esters formed duringthe metathesis reaction of phenylboronic esters MR-02-66 and MR-2016a inbulk at 150° C. is plotted as a function of time (abscissa; minutes) inFIG. 15.

Comparative Example 1: Boronic Esters that do not Undergo MetathesisReaction; Boronic Acids Pinacol Esters

Example 3: Synthesis of Monomers (M1-M3), of Cross-Linking Agents (R1and R2) and of Additives A1 and C1

3.1. Synthesis of Monomer M1

The following scheme represents the synthesis of monomer M1

3.1.1 Synthesis of Compound 1

2-Bromoethanol (15 g, 120 mmol), DIPEA (17.1 g, 132 mmol), DMAP (147 mg,1.2 mmol) and methacrylic anhydride (22.2 g, 144 mmol) are mixed(without the addition of any solvent) and stirred for 24 hours at roomtemperature (RT). Methanol (5 mL) is added and the resulting mixture isstirred for two additional hours at RT. Ethyl acetate (50 mL) and water(50 mL) are added. The resulting organic phase is washed with a 0.5 MHCl solution (3×50 mL), with a 0.5 M NaOH solution (3×50 mL) and withwater (1×50 mL). The organic phase is dried over magnesium sulfate(MgSO₄), filtered and concentrated under reduced pressure at 50° C. toyield 18.3 g of a slightly yellow liquid. ¹H-NMR analysis confirms thegeneration of compound 1 and the presence of ca. 13 mol % of ethyleneglycol dimethacrylate.

¹H NMR (CDCl₃, 400 MHz): δ 6.17 (s, 1H), 5.62 (s, 1H), 4.44 (t, J=6.0Hz, 2H), 3.56 (t, J=6.0 Hz, 2H), 1.95 (s, 3H).

3.1.2 Synthesis of Compound 2

4-Carboxyphenylboronic acid (5 g, 30.1 mmol) and propane-1,2-diol (2.41g, 31.7 mmol) are mixed in diethyl ether (Et₂O, 30 mL) and 0.1 ml ofwater is added. The resulting mixture is stirred until full dissolutionof compounds. Magnesium sulfate (5 g) is added and the suspension isstirred for 24 hours at RT before filtration. The filtrate isconcentrated under reduced pressure to yield compound 2 as a white solid(5.15 g).

¹H NMR (CDCl₃, 400 MHz): δ 7.97 (d, J=8.4 Hz, 2H), 7.78 (d, J=8.4 Hz,2H), 4.79-4.68 (m, 1H), 4.44 (t, J=8.4 Hz, 1H), 3.87 (d, J=8.4 Hz, 1.6Hz, 1H), 1.33 (d, J=6.4 Hz, 3H).

3.1.3 Synthesis of Compound 3

Compound 1 (5 g, 25.9 mmol), compound 2 (6.14 g, 29.8 mmol) and K₂CO₃(10.7 g, 77.7 mmol) are mixed in 50 mL de N,N-dimethylformamide (DMF).The resulting mixture is stirred at 70° C. for 5 hours. Ethyl acetate(50 mL) and water (150 mL) are added and the organic phase is washedwith water (3×150 mL). During washing, 300 mg of sodium chloride (NaCl)are added to the mixture to enhance phase separation. The organic phaseis dried over magnesium sulfate, filtered and concentrated under reducedpressure at 50° C. to yield a white solid. The white solid is dissolvedin 50 mL of ethyl acetate and the resulting solution is washed with HCl0.5 M (3×25 mL) and water (1×50 mL). The organic phase is dried overmagnesium sulfate, filtered and concentrated under reduced pressure at50° C. to yield a white solid (4.73 g). A fraction of the white solid(1.15 g) is dissolved in ethyl acetate. The resulting mixture is heatedto 50° C. and 8.5 mL heptane is added. The mixture is kept 5 minutes at50° C. before being placed in a freezer at −18° C. After 16 hours, theprecipitated white solid is collected via filtration and washed with 250mL pentane. This procedure is repeated a second time to obtain compound3 (529 mg) as a white solid.

¹H NMR (CDCl₃, 400 MHz): δ 8.31 (s, 2H), 7.91 (s, 2H), 6.02 (s, 1H),5.67 (s, 1H), 4.57-4.45 (m, 4H), 1.87-1.79 (m, 3H).

3.1.4 Synthesis of Compound 4 or Monomer M1

Compound 3 (3 g, 10.8 mmol), propane-1,2-diol (0.86 g, 11.3 mmol) aremixed in 30 mL diethyl ether and 0.1 mL water is added. The resultingmixture is stirred until complete dissolution of compounds. Magnesiumsulfate (4 g) is added and the mixture is stirred for 24 hours at RTbefore being filtered. The filtrate is concentrated under reducedpressure yielding compound 4 or monomer M1 as a white solid (3.18 g).

¹H NMR (CDCl₃, 400 MHz): δ 8.02 (s, 2H), 7.88 (s, 2H), 6.13 (s, 1H),5.58 (s, 1H), 4.75-4.49 (m, 6H), 3.93 (s, 1H), 2.16 (s, 3H), 1.42 (s,3H).

3.2. Synthesis of Monomer M2

The following scheme represents the synthesis of monomer M2.

3.2.1 Synthesis of Compound 5

Hexane-1, 2, 6-triol (25 g, 186 mmol) is dissolved in 340 mL of acetoneand 45 g of magnesium sulfate are added. p-Toluenesulfonic acid (pTSA,2.99 g, 15.7 mmol) is added gradually while stirring. After completeaddition, the reaction mixture is stirred for 24 hours at RT. NaHCO₃(2.66 g, 31.7 mmol) is added and the mixture is stirred for 3 additionalhours at RT. The suspension is filtered and the filtrate is concentratedunder reduced pressure to yield a heterogeneous white mixture. Water(350 mL) is added and the resulting mixture is extracted withdichloromethane (4×200 mL). The combined organic phases is dried overmagnesium sulfate, filtered and concentrated under reduced pressure toobtain compound 5 (28.7) as a slightly yellow liquid.

¹H NMR (CDCl₃, 400 MHz): δ 4.01-3.91 (m, 2H), 3.49 (t, J=6.4 Hz, 2H),3.40 (t, J=7.2 Hz, 1H), 2.80 (s, 1H), 1.60-1.35 (m, 6H), 1.30 (s, 1H),1.24 (s, 1H).

3.2.2 Synthesis of Compound 6 or Monomer M2

Compound 5 (14.3 g, 82.2 mmol), DIPEA (11.7 g, 90.5 mmol), DMAP (100 mg,0.82 mmol) and methacrylic anhydride (15.2 g, 98.8 mmol) are mixed(without any additional solvent) and stirred at RT for 24 hours.Methanol (5 mL) is added and the resulting mixture is stirred at RT fortwo additional hours. Heptane (50 mL) and water (50 mL) are added. Theresulting organic phase is washed with HCl 0.5 M (3×50 mL) and water(1×50 mL). The organic phase is dried over magnesium sulfate, filteredand concentrated under reduced pressure at 50° C. to yield the monomerM2 (15.2 g) as a slightly yellow liquid.

¹H NMR (CDCl₃, 400 MHz): δ 6.03 (s, 1H), 5.49 (s, 1H), 4.09-3.95 (m,4H), 3.43 (t, J=7.2 Hz, 1H), 1.88 (s, 3H), 1.68-1.28 (m, 12H).

3.3. Synthesis of Monomer M3

The following scheme represents the synthesis of monomer M3.

Hexane-1,2,6-triol (10 g, 74.5 mmol) and phenylboronic acid (9.55 g,78.3 mmol) are mixed in a mixture of 50 mL of acetone and 0.2 mL ofwater. Magnesium sulfate (20 g) is added and the resulting suspension isstirred at RT for 24 hours before being filtered. The filtrate isconcentrated under reduced pressure to yield compound 7 (13.6 g) as acolorless liquid.

¹H NMR (CDCl₃, 400 MHz): δ 7.82 (d, J=8.0 Hz, 2H), 7.50-7.46 (m, 1H),7.40-7.36 (t, J=8.0 Hz, 2H), 4.61-4.54 (m, 1H), 4.43 (dd, J=8.8 Hz, 0.8Hz, 1H), 3.95 (dd, J=8.8 Hz, 2.0 Hz, 1H), 3.67 (t, J=6.4 Hz, 2H),1.76-1.47 (m, 6H).

3.3.2 Synthesis of Compound 8

Compound 7 (5.0 g, 22.7 mmol), DIPEA (3.23 g, 25.0 mmol), DMAP (28 mg,0.23 mmol) and methacrylic anhdyride (4.2 g, 27.3 mmol) are mixed(without the addition of solvent) and stirred at RT for 24 hours.Methanol (1 mL) is added and the resulting mixture is stirred at RT fortwo additional hours. Ethyl acetate (50 mL) and water (50 mL) are added.The resulting organic phase is washed with a 0.5 M HCl solution of (3×50mL), a 0.5 M NaOH solution (3×50 mL) and water (1×50 mL). The organicphase is dried over magnesium sulfate, filtered and concentrated underreduced pressure to yield compound 8 (3.03 g), with few impuritiesdetectable by 1H NMR, as a slightly yellow liquid.

3.3.3 Synthesis of Compound 9 or Monomer M3

Compound 8 (700 mg, 3.46 mmol) and phenylboronic acid (443 mg, 3.63mmol) are mixed in a mixture of 20 mL of diethyl ether and 0.1 mL ofwater. Magnesium sulfate (1 g) is added and the resulting suspension isstirred at RT for 5 hours before filtration. The filtrate isconcentrated under reduced pressure to yield monomer M3 (864 mg), withfew impurities detectable by 1H NMR, as a slightly yellow liquid thatcrystallizes rapidly.

3.4 Compound of Formula (Ia): Synthesis of Compound 10 or Cross-LinkingAgent R1

1,4-Phenylenebisboronic acid (3.0 g, 18.1 mmol) and propane-1,2-diol(2.82 g, 37.1 mmol) are mixed in a mixture of 30 mL of THF and 0.1 mL ofwater. Magnesium sulfate (5 g) is added, the reaction mixture is stirredat RT for 24 hours, filtered and concentrated under reduced pressure toobtain a slightly yellow solid. The solid is put in heptane and theresulting suspension is stirred at 50° C. for 1 hour before filtration.The filtrate is concentrated under reduced pressure to obtain thecross-linking agent R1 (4.06 g, 1, 2 propanediol content<0.7 mol % bygas chromatography) as a white solid.

¹H NMR (CDCl₃, 400 MHz): δ 7.82 (s, 4H), 4.77-4.69 (m, 2H), 4.46 (dd,J=8.8 Hz, 1.2 Hz, 2H), 3.90 (dd, J=8.8 Hz, 1.2 Hz, 2H), 1.41 (d, J=6.4Hz, 6H).

3.5 Compound of Formula (Ia): Synthesis of Compound 11 or Cross-LinkingAgent R2

1,4-Phenylenediboronic acid (3.0 g, 18.1 mmol) and butane-1,3-diol (3.43g, 38.0 mmol) are mixed in a mixture of 30 mL THF and 0.1 mL water.Magnesium sulfate (6 g) is added, the reaction mixture is stirred at RTfor 24 hours, filtered and concentrated under reduced pressure to obtainthe cross-linking agent R2 as a white solid (3.97 g, 14.5 mmol).

¹H NMR (THF-d₈, 400 MHz): δ 7.65 p.p.m. (s, 4H), 4.28-4.23 (m, 2H),4.14-4.03 (m, 4H), 2.02-1.97 (m, 2H), 1.79-1.74 (m, 2H), 1.31 (d, J=6.4Hz, 6H).

¹³C NMR (THF-d₈, 100 MHz): δ 130.5, 65.7, 59.1, 32.4, 20.4.

3.6. Synthesis of Compound 13 or Additive A1

Compound 12 was synthesized according to literature (1). Compound 12(5.5 g, 23.1 mmol) and phenylboronic acid (2.8 g, 23.1 mmol) weredissolved in toluene and heated for 6 hours under reflux conditions(T=135° C.) with Dean-Stark equipment to trap water. Afterwards, themixture was cooled to room temperature and the solvent was removed undervacuum. The residue was dissolved in ethanol and the mixture stored at−5° C., after which the compound 13 or additive A1 crystallized as ayellow solid (m=4.8 g, 81%).

¹H-NMR (DMSO-d₆, 400 MHz): δ 7.66 (d, J=8 Hz, 2H), 7.51 (t, J=7.2 Hz,1H), 7.40 (t, J=7.6 Hz, 2H), 7.07 (s, 2H), 4.75 (ddt, J=8.0, 6.0, 5.6Hz, 1H), 4.39 (dd, J=9.6, 8.0 Hz, 1H), 4.11 (dd, J=9.6, 5.6 Hz, 1H),3.67 (d, J=6 Hz, 2H).

¹³C-NMR (DMSO-d₆, 100 MHz): δ 170.9, 134.6, 134.4, 131.5, 127.8, 74.4,68.5, 41.3.

GC-ESI-MS: (m/z) calc for C13H12BNO4 257.09, found 257.

3.7. Synthesis of Compound 14 or Additive C1

Compound 12 was synthesized according to literature (1). Compound 12 (4g, 16.7 mmol) and 1,4-phenylenediboronic acid (1.38 g, 8.4 mmol) weredissolved in toluene and heated for 6 hours under reflux conditions(T=135° C.) with a Dean-Stark equipment to trap water. A white solidprecipitate appeared, along with a small amount of yellow/orange residuesticking to the flask. The solution with the white powder was separatedfrom the residue and concentrated under vacuum. ¹H-NMR analysis inDMSO-d₆ provided evidence for full esterification but only partial retroDiels-Alder reaction. The solid was dissolved in 50 mL oforthodichlorobenzene (ODCB) at 140° C. and stirred for 18 hours.Afterwards, the solvent was removed under vacuum yielding compound 14 oradditive C1 as an off-white solid. Yield=2.5 g. n=69.9%.

¹H NMR (DMSO-d₆, 400 MHz): δ 7.65 (s, 4H), 7.06 (s, 4H), 4.74 (ddt,J=7.6, 6.0, 5.6 Hz, 2H), 4.38 (t, J=8.8 Hz, 2H), 4.1 (dd, J=9.6 Hz, 6.0Hz, 1H), 3.67 (d, J=5.6 Hz, 2H).

¹³C NMR (DMSO-d6, 400 MHz): δ 170.9, 134.6, 132.1, 74.4, 68.5, 41.3.

Example 4: Synthesis of Polymers P1 and P2 of the Invention and Polymersfor Comparative Examples

4.1. Example of Procedure for the Synthesis of a Polymer P1 ViaRAFT-Polymerization (“Reversible Addition-Fragmentation Chain TransferPolymerization”): Polymer P1a

Methyl methacrylate (MMA, 1.26 &g, 12.6 mmol), monomer M1 (1 g, 3.14mmol), 2-phenyl 2-propyl benzodithioate (PPBDT, 17.2 mg, 0.063 mmol) andAIBN (4.1 mg, 0.025 mmol) are mixed in 1.5 mL of anisole. The resultingsolution is bubbled with nitrogen at RT for 30 minutes. The reactionmixture is heated to 65° C. for 16 hours while keeping it under nitrogenatmosphere. After 16 hours, 2 mL of anhydrous THF is added and thepolymer is precipitated into dry diethyl ether. The obtained polymer isredissolved in anhydrous THF and precipitated a second time into drydiethyl ether. The polymer P1a (Mn=43 kg/mol, Ip=1.32) is dried underhigh vacuum at 50° C. over night.

4.2. Example of Procedure for the Synthesis of a Polymer Polyacetal ViaRAFT-Polymerization RAFT: Polymers P3a and P3b

MMA (5.0 g, 49.9 mmol), monomer M2 (3.0 g, 12.5 mmol), 2-phenyl 2-propylbenzodithioate (PPBDT, 68.0 mg, 0.25 mmol) and AIBN (16.4 mg, 0.1 mmol)are mixed in 5 mL of anisole. The resulting solution is bubbled withnitrogen at RT for 30 minutes. The reaction mixture is heated to 65° C.for 16 hours while keeping it under nitrogen atmosphere. After 16 hours,5 mL of anhydrous THF is added and the polymer is precipitated into drydiethyl ether. The obtained polymer is redissolved in anhydrous THF andprecipitated a second time into dry diethyl ether. The polymer P3a(Mn=39 kg/mol, Ip=1.22) is dried under high vacuum at 50° C. over night.

Using the same polymerization temperature, time and initial ratio(volume) of monomers/anisole, but changing the initial molar ratioMMA/M2/PPBDT/AIBN=800/200/1/0.4 (instead of 200/50/1/0.4), a polymer P3b(Mn=86 kg/mol, Ip=1.53) is obtained.

4.3. Example of Procedure for the Elimination of the Dithioester ChainEnd of a Polymer Prepared by RAFT-Polymerization: Polymer P3a*

The polymer P3a (14 g) is dissolved in 300 mL anhydrous THF andn-butylamine (41.6 mg, 0.57 mmol) is added. The resulting mixture isstirred at RT for 24 hours, before addition of ethyl acrylate (120 mg,1.2 mmol). The reaction mixture is stirred at RT for 24 hours. PolymerP3a* is then recovered by precipitation into methanol and filtration,before being dried under high vacuum at 50° C. over night. 12 g ofpolymer P3a* is thus obtained.

4.4. Functionalization of the Polyacetal P3a Polymer, Respectively P3b,to Prepare a Polymer P1 or P2 of the Invention, Named P2a, RespectivelyP2b, and Preparation of Polymer P5a (from P3a) Used for ComparativeExamples.

The following scheme represents the synthesis of the polymers P2a,respectively P2b, P4a, respectively P4b, and P5a from polyacetal P3a,respectively P3b.

4.4.1. Example of Procedure for the Synthesis of a Polydiol Polymer froma Polyacetal Polymer: Polymer P4a and P4b

The polyacetal P3a (1.0 g) is dissolved in dioxane (50 mL) and 0.5 mL ofa 1 M HCl solution and 0.4 mL of a 36 wt % HCl solution are added. THF(3 mL) is added and the reaction mixture is stirred at RT for 48 hours.The solution is concentrated under reduced pressure and the polymer isisolated by precipitation into dry diethyl ether. The resulting polymeris re-dissolved in THF and precipitated a second time into dried diethylether. The polydiol polymer P4a is dried under high vacuum at 50° C.over night. Via the same method, but using polyacetal P3b instead ofPSa, the polydiol polymer P4b is obtained.

4.4.2 Example of Procedure for the Synthesis of Polymer P1 or P2 of theInvention from a Polydiol Polymer: Polymers P2a and P2b

Phenylboronic acid (232 mg, 1.9 mmol) and polymer P4a (1.0 g) are mixedin 25 mL of anhydrous THF and water (0.1 mL) is added. The reactionmixture is stirred at RT until full dissolution. Magnesium sulfate (4 g)is added and the reaction mixture is stirred 5 hours at RT before beingfiltered. The filtrate is concentrated under reduced pressure (viscoussolution). The polymer P2a is isolated by precipitation of this viscoussolution into dried diethyl ether and then dried at 50° C. under highvacuum over night. Via the same procedure, but using the polydiol P4binstead of P4a, the polymer P2b is obtained.

4.4.3 Example of Procedure for the Synthesis of a Polydiol Polymer withits Hydroxyl-Functionalities Protected as Silyl Ethers, Used forComparative Examples: Polymer PSa

The polymer P4a (1 g) is dissolved in 20 mL of THF and the reactionmixture is cooled to 0° C. While keeping the temperature at 0° C.,triethylamine (733 mg, 7.24 mmol) is added and thenchlorotrimethylsilane (590 mg, 5.43 mmol) is added dropwise. Thereaction mixture is allowed to warm to RT and stirred for 6 additionalhours at RT. After filtration, the polymer P5a is isolated byprecipitation into dried diethyl ether and dried under high vacuum at50° C. over night.

4.5. Example of Procedure for the Synthesis of a Polymer P1 or P2 of theInvention Via RAFT-Polymerization: Polymer P2c, P2d, P2e and P2f

4.5.1. General Procedure for the Synthesis of a Polymer P1 or P2 of theInvention Via RAFT-Copolymerization of Monomer 3: Polymer 2c

Synthesis of Poly(Methyl Methacrylate) with Pending Dioxaborolanes:Polymer 2c.

MMA (1.22 g, 12.2 mmol), the monomer M3 (880 mg, 3.05 mmol), 2-phenyl2-propyl benzodithioate (16.7 mg, 0.061 mmol) and AIBN (4.0 mg, 0.024mmol) were dissolved in anisole (1.2 mL). The resulting mixture wasbubbled with nitrogen at room temperature for 30 minutes before beingheated to 65° C. The reaction mixture was kept under nitrogen whilebeing stirred at 65° C. After 16 hours, 1 mL of THF was added to theviscous oil and the mixture was precipitated into dry diethyl ether(Et₂O). The polymer 2c was dried at 100° C. under high vacuum for 16hours. Yield=1.2 g. M_(n)=24 300 g/mol, Ð=1.18.

4.5.2. General Procedure for the Synthesis of a Polymer P1 or P2 of theInvention Via RAFT-Copolymerization of Compound 8: Polymer 2d andPolymer P4e

Synthesis of Poly(Methyl Methacrylate) with Pending DiolFunctionalities: Polymer P4c.

MMA (15 g, 149.8 mmol), compound 8 (7.58 g, 37.5 mmol), 2-phenyl2-propyl benzodithioate (51.0 mg, 0.187 mmol) and AIBN (12.3 mg, 0.075mmol) were dissolved in anisole (15 mL). The resulting mixture wasbubbled with nitrogen at room temperature for 30 minutes before beingheated to 65° C. The reaction mixture was kept under nitrogen whilebeing stirred at 65° C. After 16 hours, 10 mL of THF were added to theviscous oil and the mixture was precipitated into dry diethyl ether(Et₂O). Yield=17.5 g. Total monomer conversion: 77%. M_(n)=71 000 g/mol,Ð=1.35.

Synthesis of Poly(Methyl Methacrylate) with Pending Dioxaborolanes:Polymer 2d.

Polymer P4c (17 g, 31.9 mmol diols, 0.274 mmol chains) was dissolved inTHF (250 mL) and phenylboronic acid (4.08 g, 33.5 mmol) and water (0.1mL) were added. After 5 minutes, MgSO₄ (11.5 g) was added and themixture was stirred at room temperature for 5 hours. AIBN (173 mg, 1.06mmol) was added and the mixture heated for 6 hours at 60° C. and then 9additional hours at room temperature. Triphenylphosphine (277 mg, 1.06mmol) was added and the reaction mixture was stirred at 40° C. for 1additional hour. The mixture was put in a centrifuge for 30 minutes at8500 rpm, filtered, concentrated under reduced pressure and precipitatedfrom dry Et₂O. The polymer 2d was dried at 100° C. under high vacuum for16 hours. Yield=14.5 g. Ratio Diol/MMA 1/3.3 from monomer conversions.M_(n)=86 000 g/mol, Ð=1.40.

Synthesis of Polystyrene with Pending Diol Functionalities: Polymer P4d.

Styrene (43 mL, 376 mmol), compound 8 (7.6 g, 37.6 mmol) and 2-phenyl2-propyl benzodithioate (102 mg, 0.376 mmol) were mixed with anisole(0.7 mL) and bubbled with argon at room temperature for 30 minutes. Themixture was heated to 140° C. for 6 hours and samples were taken tofollow the reaction kinetics. After 6 hours, the mixture was dilutedwith THF and precipitated from methanol (MeOH). The polymer was filteredand dried under reduced pressure to obtain polymer P4e as a pink solid(35 g, yield 75%). Conversion of compound 8=85.7%, conversion ofstyrene=73.1%, ratio diol methacrylate/styrene from conversions: 1/8.5.M_(n)=75 000 g/mol, Ð=1.57.

Synthesis of Polystyrene with Pending Diol Functionalities without RAFTChain-Ends: Polymer P4e.

Polymer P4d was dissolved in a 1/1 THF/DMF mixture (250 mL) and reactedwith n-butyl amine (275 mg, 3.76 mmol) at room temperature under argonfor 5 hours. n-Butylacrylate (4.8 g, 37.6 mmol) was added to thereaction mixture and stirring was continued for 18 hours at roomtemperature. The mixture was concentrated under reduced pressure and thecolorless polymer P4e was precipitated from MeOH (ca 30 g). M_(n)=77 000g/mol, Ð=1.60.

Synthesis of Polystyrene with Pending Dioxaborolanes: Polymer P2e.

The polymer P4e (25 g, 23.8 mmol pending diols) was dissolved in THF (50mL) and phenylboronic acid (2.94 g, 24.1 mmol) and MgSO₄ (8.68 g, 72.4mmol) were added. After 5 hours at room temperature, the mixture wascentrifuged and then filtered, concentrated under reduced pressure andprecipitated from dry Et₂O to yield polymer P2e. M_(n)=76 000 g/mol,Ð=1.71.

4.5.3. General Procedure for the Synthesis of a Polymer P1 or P2 of theInvention: Polymer 2f

Synthesis of Poly(Methyl Methacrylate) with Pending Dioxaborolanes:Polymer 2f.

Cyclohexylboronic acid (1.20 g, 9.8 mmol) and 5.0 g of a polydiol PMMAwith a M_(n) of 100 kg/mol, a Ð of 1.2 and 17 mol % of monomer unitscarrying a diol function, which was prepared following a procedure basedon the procedure used to prepare Polymer P4c, are mixed in 25 mL ofanhydrous THF and 0.1 mL of water is added. The reaction mixture isstirred at RT until full dissolution of all compounds. Magnesium sulfate(5 g) is added and the reaction mixture is stirred 5 hours at RT beforebeing filtered. The filtrate is concentrated under reduced pressure togive a viscous solution. The polymer P2f is then isolated byprecipitation of the viscous solution into dried diethyl ether andfiltration. The polymer P2f is subsequently dried at 50° C. under highvacuum over night. Yield=4 g. M_(n)=103 000 g/mol, Ð=1.25.

4.6. Functionalization of Commercial High-Density Polyethylene (HDPE)with Compound 13 or Additive A1 to Prepare a Polymer P1 or P2 of theInvention.

4.6.1. Melt Functionalization of Commercial High-Density Polyethylene(HDPE) with Compound 13 or Additive A1 to Prepare a Polymer P1 or P2 ofthe Invention, Named P2g.

Functionalization of commercial high-density polyethylene (HDPE) wascarried out using a DSM Explore batch twin-screw extruder (5 cm³capacity) equipped with co-rotating conical screw profile andrecirculation channel to control the residence time. High-densitypolyethylene (HDPE) was purchased from Sigma Aldrich (referenced as428078, melt index 2.2 g/10 min at 190° C. for 2.16 kg). Dry blends ofHDPE, compound 13 or additive A1 (6 wt %) and dicumyl peroxide (0.3 wt%) were prepared prior to introduction in the extruder. Melt graftingwas performed under nitrogen atmosphere with a barrel temperature of200° C., a screw speed of 100 rpm and a residence time of 10 minutes.Extrudates were collected and let to cool down to room temperature. FTIRanalysis of the polymer P2g indicates that this polymer containsapproximately 4.5 weight % of compound 13 or additive A1.

4.6.2. Solution Functionalization of Commercial High-DensityPolyethylene (HDPE) with Compound 13 or Additive A1 to Prepare a PolymerP1 or P2 of the Invention, Named P2i-P2l.

2 g of HDPE (purchased from Sigma Aldrich, referenced as 428078, meltindex 2.2 g/10 min at 190° C. for 2.16 kg) was charged in a sample vialwith orthodichlorobenzene (ODCB) (10 mL) and a stirrer bar. The vial wascapped and heated to 140° C. under stirring to dissolve the polymer. 2weight % (as compared to HDPE) of compound 13 or additive A1,respectively 4 wt %, respectively 6 wt %, respectively 8 wt %,respectively 10 wt %, was added to the mixture and stirred untileverything was dissolved. The mixture was then heated to 160° C. Asolution of ditertbutyl peroxide (75 μL in 2 mL ODCB) was prepared and0.2 mL of this solution was added to the polymer solution to initiatethe grafting process. After 1 hour at 160° C., the reaction mixture wasprecipitated from acetone. The crude polymer was boiled in acetone andfiltered twice, after which it was dried under vacuum to constant weightto yield the polymer P2h, respectively P2i, respectively P2j,respectively P2k, respectively P2l. FTIR analysis of the polymer P2h,respectively P2i, respectively P2j, respectively P2k, respectively P2l,indicates that this polymer contains approximately 0.5 weight %,respectively approximately 2.5 weight %, respectively approximately 4.2weight %, respectively approximately 5.7 weight %, respectivelyapproximately 7 weight %, of compound 13 or additive A1.

Example 5. Formation and Characterization of Cross-Linked PolymerNetworks Containing Pending Exchangeable Bonds and Cross-LinksExchangeable by Metathesis Reaction of Boronic Esters According to theInvention and Formulations Serving as Comparative Examples

5.1.1 Example of Liquid Formulation Yielding a Cross-Linked PolymerNetwork from Polymers P1 (P1a) and P2 (P2a) According to the Invention.

The following example represents a liquid formulation according to theinvention and illustrates the formation of a cross-linked polymernetwork in solution.

0.1 g of polymer P1a is dissolved at RT in 0.6 mL of anhydrous THF. 0.1g of polymer P2a is dissolved at RT in anhydrous THF. The two solutionscontaining the dissolved polymers in anhydrous THF are mixed at RT andthe formation of a gel, or cross-linked polymeric network swollen withTHF, is observed in less than 5 minutes after mixing.

5.1.2 Comparative Examples of Liquid Formulations Containing a PolymerP1 (P1a) and a Polymer Containing Pending Acetal Groups, P3a, or aPolymer Containing Pending Silyl Ether Groups Obtained from Diols, P5a.

The following comparative examples illustrate the fact that thecross-linking reaction proceeds by metathesis reaction of boronicesters.

0.1 g of polymer P1a is dissolved in 0.6 mL of anhydrous THF at RT. 0.1g of polymer P3a is dissolved in 0.6 mL of anhydrous THF at RT. The twosolutions containing the dissolved polymers in anhydrous THF are mixedat RT. Gel formation is not observed at RT, neither after 5 minutes norafter 24 hours after mixing.

0.1 g of polymer P1a is dissolved in 0.6 mL of anhydrous THF at RT. 0.1g of polymer P5a is dissolved in 0.6 mL of anhydrous THF at RT. The twosolutions containing the dissolved polymers in anhydrous THF are mixedat RT. Gel formation is not observed at RT, neither after 5 minutes norafter 24 hours after mixing.

5.1.3 Example of a Liquid Formulation of a Cross-Linked Polymer Networkfrom Polymers P1 (P2a) and a Compound of Formula (Ia) (Cross-LinkingAgent R1) According to the Invention.

The following example presents a liquid formulation and illustrates theformation of a cross-linked polymer network in solution according to theinvention.

0.1 g of polymer P2a and 4.5 mg of the cross-linking agent R1 aredissolved in 1.2 mL of anhydrous THF at RT in a closed glass vial. Thereaction mixture is heated to 50° C. After 1 hour at 50° C. theformation of a gel, or a cross-linked polymer network swollen with THF,is observed.

5.1.4 Comparative Examples of Liquid Formulations Containing a Compoundof Formula (Ia) (Cross-Linking Agent R1) According to the Invention anda Polymer Containing Pending Acetal Functionalities, P3a, or a PolymerContaining Pending Silyl Ether Functionalities Obtained from Diols, P5a.

The following comparative examples illustrate the fact that thecross-linking reaction proceeds by metathesis reaction of boronicesters.

0.1 g of polymer P3a and 4.5 mg of the cross-linking agent R1 aredissolved in 1.2 mL of anhydrous THF at RT in a closed glass vial. Thereaction mixture is heated to 50° C. After 1 hour at 50° C. gelformation is not observed.

0.1 g of polymer P5a and 4.5 mg of the cross-linking agent R1 aredissolved in 1.2 mL of anhydrous THF at RT in a closed glass vial. Thereaction mixture is heated to 50° C. After 1 hour at 50° C. gelformation is not observed.

5.2. Example of a Solid Formulation, Processing Via Compression Molding,Insolubility and Recycling Tests of a Cross-Linked Polymer Network

The following example represents a solid formulation and illustrates theformation of a cross-linked polymer network according to the invention,its processing via compression molding and its insolubility in a goodnon-reactive solvent of the polymer constituting the cross-linkedpolymer network.

Formation, Processing Via Compression Molding of a Cross-Linked PolymerNetwork: N1, N2, N3, N4, N5 and N6

10.0 g of polymer P2a are dissolved in 10 mL of anhydrous THF at RT and220 mg of formula (Ia) R1 compound are added. The reaction mixture isstirred slowly at RT during 30 minutes before being concentrated underreduced pressure at 120° C. and then dried under high vacuum for 3 to 5hours at 120° C. The resulting polymer is ground into powder andcompression molded during 1 hour at 150° C. under a pressure of 3 to 5tons. The resulting cross-linked polymer network is named N1.

Via the same procedure, but using polymer P2b (instead of P2a), thecross-linked polymer network N2 is obtained.

Via the same procedure, but using polymer P2b (instead of P2a) and using100 mg of formula (Ia) R1 compound (instead of 220 mg), the cross-linkedpolymer network N3 is obtained.

Via the same procedure, but using polymer P2c (instead of P2a), thecross-linked polymer network N4 is obtained.

Via the same procedure, but using polymer P2d (instead of P2a) and using100 mg of formula (Ia) R1 compound (instead of 220 mg), the cross-linkedpolymer network N5 is obtained.

Via the same procedure, but using polymer P2d (instead of P2a), thecross-linked polymer network N6 is obtained.

Solubility Tests of the Cross-Linked Polymer Network N2 at RT in THF

A sample of the cross-linked polymer network N2 is added to 10 mL ofanhydrous THF and swollen for 24 hours at RT. The sample is weighted,dried under high vacuum at 100° C. until constant weight (ca. 24 hours).The swelling ratio (SR) and the soluble fraction (SF) of thecross-linked polymer network N2 are calculated. This experiment is doneon three samples and the results are reported in table 1, below.

Swelling ratio=(mass of the swollen sample−mass of the dried sampleafter swelling)/(mass of the dried sample after swelling)

Soluble fraction=(mass of the dry sample before swelling−mass of thedried sample after swelling)/(mass of the dried sample after swelling)

TABLE 1 Mass before Mass Mass dried Soluble swelling swollen Swellingafter swelling fraction Sample [mg] [mg] ratio [mg] [%] 1 73 352 4.1 695.8 2 102 496 4.1 97 5.2 3 146 601 3.26 141 3.5

5.3. Recycling of a Cross-Linked Polymer Network after Processing ViaCompression Molding/Mechanical Testing/Grinding to Powder

The following example represents a solid formulation, its mechanicalcharacterization, its processing via compression molding, andillustrates the aptitude of the cross-linked polymer networks describedin the invention to be recycled several times without significantdegradation of their mechanical properties.

Samples obtained from the cross-linked polymer network N1 with the adumbbell shape were tested in traction using a tensile testing deviceInstron 5564. The samples were elongated until rupture with a cross-headspeed of 1.5 mm/min, ground into powder and re-processed via compressionmolding under a pressure between 3 to 5 tons for 30 minutes at 150° C.This procedure was repeated 3 times on 4 samples.

FIG. 16 represents the stress at break (ordinate, MPa) of samples of thecross-linked polymer network N1 not recycled (abscissa, 0), of samplesof the cross-linked polymer network N1 recycled 1 time (abscissa, 1), ofsamples of the cross-linked polymer network N1 recycled 2 times(abscissa, 2), of samples of the cross-linked polymer network N1recycled 3 times (abscissa, 3).

This analysis indicates that the stress at break of the cross-linkedpolymer network N1 does not decrease significantly after severalrecycling and re-processing cycles.

FIG. 17 represents the elongation at break (ordinate, %) of samples ofthe cross-linked polymer network N1 not recycled (abscissa, 0), ofsamples of the cross-linked polymer network N1 recycled 1 time(abscissa, 1), of samples of the cross-linked polymer network N1recycled 2 times (abscissa, 2), of samples of the cross-linked polymernetwork N1 recycled 3 times (abscissa, 3).

This analysis indicates that the elongation at break of the cross-linkedpolymer network N1 does not decrease significantly after severalrecycling and re-processing cycles.

5.4. Creep Tests of Cross-Linker Polymer Networks N1 and N2

The following example illustrates the possibility to reshape thecross-linked polymer networks described in the invention afterprocessing via compression molding.

Samples of the cross-linked polymer network N1 and of the cross-linkedpolymer network N2 were tested for creep in an ARES G2 rheometer from TAInstruments. The samples with disc shape of the cross-linked polymernetwork N1 were put under a stress of 1000 Pa at 4 differenttemperatures (160° C., 150° C., 140° C., 130° C.) for ca. 20 minutes.After ca. 20 minutes, the stress was released and the samples were keptat the respective temperature for ca. 10 minutes.

A sample of the cross-linked polymer network N2 with a disc shape wasput under a stress of 1000 Pa at 160° C. for ca. 30 minutes. After ca.30 minutes, the stress was released and the sample was kept at 160° C.for ca. 30 minutes.

FIG. 18 represents the deformation (ordinate, %) as a function of time(abscissa, min), for 4 temperatures (160° C. circles; 150° C. triangles;140° squares; 130° C. stars), of samples of the cross-linked polymernetwork N1.

FIG. 19 represents the deformation (ordinate, %) in time (abscissa,min), at 160° C. of samples of the cross-linked polymer network N2.

These experiments indicate that the cross-linked polymer networks N1 andN2 flow at a temperature greater than the glass transition temperature(Tg) or fusion (Tf), advantageously greater than Tg or Tf+10° C., moreadvantageously greater than Tg or Tf+20° C., even more advantageouslygreater than Tg or Tf+40° C., even more advantageously greater than Tgor Tf+80° C., if the glass transition temperature or the fusiontemperature is lower than 25° C.

These experiments also indicate that after releasing the stress, thesamples present a permanent deformation of several % that corresponds totheir new equilibrium state. It is thus possible to give new shapes tocross-linked polymer networks N1 and N2.

5.5. Stress Relaxation Tests of Cross-Linked Polymer Networks N1, N2 andN3

The following examples illustrate the ability of the cross-linkedpolymer networks described in the invention to totally or partiallyrelax the stresses present in the material at a temperature greater thanthe glass transition temperature (Tg) or fusion (Tf), advantageouslygreater than Tg or Tf+10° C., more advantageously greater than Tg orTf+20° C., even more advantageously greater than Tg or Tf+40° C., evenmore advantageously greater than Tg or Tf+80° C., if the glasstransition temperature or the fusion temperature is lower than 25° C.

The stress relaxation experiments were performed in an Ares G2 rheometerwith parallel plate geometry with a diameter of 25 mm. The rheometer isheated to 150° C. and equilibrated at this temperature for 5 minutes.The samples are placed between the two plates, equilibrated for 5minutes and a normal force of 10-15 N is applied. After 5 minutes, adeformation of 3% is applied and the evolution of the stress as afunction of time is monitored.

FIG. 20 represents the shear relaxation modulus normalized by theinitial modulus at t=0 (ordinate, without unit) as a function of time(abscissa, seconds) of samples of the cross-linked polymer network N1 at170° C. (square), at 150° C. (circle), at 130° C. (triangle).

FIG. 21 represents the shear relaxation modulus normalized by theinitial modulus at t=0 (ordinate, without unit) as a function of time(abscissa, seconds) at 150° C., of samples of the cross-linked polymernetwork N1 (circle), of samples of the cross-linked polymer network N2(triangle), of samples of the cross-linked polymer network N3 (square).

These experiments indicate that the cross-linked polymer networksdescribed in the invention can entirely or partially relax stresspresent in the material at a temperature greater than the glasstransition temperature of the polymers.

5.6. Processing of the Cross-Linked Polymer Network N2 Via InjectionMolding

The following example illustrates the possibility to process thecross-linked polymer networks described in the invention via injectionmolding.

1 g of the cross-linked polymer network N2 is injection molded using aninjection molding machine DSM Xplore micro 10 cc and a mold with adumbbell geometry (length ca 7 cm). The mold is heated to 200° C. beforeinjection. The cross-linked polymer network N2 to be injected isintroduced as a powder at RT into the injection molding machine. Thepolymer is heated to 200° C. (5 minutes) and equilibrated for 5 minutes.Injection molding proceeds in 5 steps: 2×30 seconds at 10 bar pressure,followed by 2×30 seconds at 12 bar pressure and release of the pressure.After injection, the mold containing the injected cross-linked polymernetwork N2 is hold at 200° C. for 1 minute before cooling with a watersystem for 5-10 minutes.

The object hence prepared by this injection molding is insoluble inanhydrous THF (75 mL of anhydrous THF per g of material; immersed 24hours at RT).

5.7. Example of a Solid Formulation, Processing Via Compression Molding:Network NX1 and NX2

The following examples represent solid formulations and illustrate theformation of cross-linked polymer networks according to the invention,their processing via compression molding and their ability to totally orpartially relax the stresses present in the material at a temperaturegreater than the glass transition temperature (Tg) or fusion (Tf),advantageously greater than Tg or Tf+10° C., more advantageously greaterthan Tg or Tf+20° C., even more advantageously greater than Tg or Tf+40°C., even more advantageously greater than Tg or Tf+80° C., if the glasstransition temperature or the fusion temperature is lower than 25° C.

5.7.1. Formation of a Cross-Linked Polymer Network: NX1

Synthesis from the PMMA Containing Pending Cyclohexylboronic EsterFunctions (Polymer P2f) and the Cross-Linking Agent R1

2 g of polymer P2f are dissolved in 10 mL anhydrous THF at RT and 44 mgof cross-linking agent R1 (compound of formula (Ia)) are added. Thereaction mixture is stirred slowly at RT during 30 minutes before beingconcentrated under reduced pressure at 120° C. for 3 hours. Theresulting polymer is ground into powder and compression molded during 1hour at 150° C. under a pressure of 3 to 5 tons. The resultingcross-linked polymer network is called NX1.

5.7.2. Formation of a Cross-Linked Polymer Network: NX2

Synthesis from the PMMA Containing Pending Phenylboronic Ester Functions(Polymer P2c) and the Cross-Linking Agent R2

2 g of polymer P2c are dissolved in 10 mL of anhydrous THF at RT and 44mg of cross-linking agent R2 (compound of formula (Ia)) are added. Thereaction mixture is stirred slowly at RT during 30 minutes before beingconcentrated under reduced pressure at 120° C. for 3 hours. Theresulting polymer is ground into powder and compression molded during 1hour at 150° C. under a pressure of 3 to 5 tons. The resultingcross-linked polymer network is called NX2.

5.8. Stress Relaxation Tests of the Cross-Linked Polymer Networks NX1and NX2

The stress relaxation experiments were performed in an Ares G2 rheometerin parallel plate geometry with a diameter of 25 mm. The rheometer isheated to 150° C. and equilibrated for 5 minutes. The samples are placedbetween the plates, equilibrated for 5 minutes and a normal force of10-15 N is applied. After 5 minutes, a deformation of 3% is applied andthe evolution of the stress in time is monitored.

FIG. 22 represents the shear relaxation modulus normalized by theinitial module at t=0 (ordinate, without unit) as a function of time(abscissa, seconds) of the samples of the cross-linked polymer networksNX1 at 150° C. (square)

FIG. 23 represents the shear relaxation modulus normalized by theinitial module at t=0 (ordinate, without unit) as a function of time(abscissa, seconds) of the samples of the cross-linked polymer networksNX2 at 150° C. (circle).

These experiments indicate that the cross-linked polymer networksdescribed in the invention can relax stress, present in the material,totally or partially at a temperature superior to the glass transitiontemperature of the polymers.

5.9. Example of Solid Formulations: Network NY1 and NY2

The following examples represent two solid formulations and illustratethe formation of cross-linked polystyrene networks according to theinvention as well as their insolubility in a good non-reactive solventof the polymer constituting the cross-linked polymer network.

5.9.1. Formation of a Cross-Linked Polystyrene Network: NY1

Synthesis from the PSt with Pending Dioxaborolane Functions (PolymerP2e) and the Cross-Linking Agent R1

10 g of polystyrene with pending dioxaborolane functions, Polymer P2e,are dissolved in 25 mL of anhydrous THF and a solution of cross-linkingagent R1 (compound of formula (Ia)) (220 mg) in anhydrous THF (0.5 mL)is added. Gel formation is observed after 10-30 minutes at roomtemperature. The gel is dried under vacuum at 120° C. for 5 hours,ground and further dried for 16 additional hours at 120° C. undervacuum. The resulting cross-linked polymer network is called NY1.

5.9.2. Formation of a Cross-Linked Polystyrene Network: NY2

Synthesis from the PSt with Pending Dioxaborolane Functions (PolymerP2e) and the Cross-Linking Agent R1 by Reactive Extrusion

The formation of the cross-linked polystyrene network NY2 was carriedout using a DSM Explore batch twin-screw extruder (5 cm3 capacity)equipped with co-rotating conical screw profile and recirculationchannel to control the residence time. Dry blends of polystyrene withpending dioxaborolane functions, Polymer P2e, and cross-linking agent R1(compound of formula (Ia)) (2.2 wt % as compared to Polymer 2e) wereintroduced in the extruder. Cross-linking was performed under nitrogenatmosphere with a barrel temperature of 200° C., a screw speed of 100rpm and a residence time of 6 min. Extrudates were collected and let tocool down to room temperature. The resulting cross-linked polymernetwork is called NY2.

Solubility Tests of the Cross-Linked Polymer Network NY2 at RT inDichloromethane (DCM)

A sample of the cross-linker polymer network NY2 is added to 6 mL ofanhydrous dichloromethane and swollen for 24 hours at RT. The sample isweighted, dried under high vacuum at 100° C. until constant weight (ca.24 hours). The swelling ratio (SR) and the soluble fraction (SF) of thecross-linked polymer network NY2 are calculated. This experiment is doneon three samples and the results are reported in table 2, below.

Swelling ratio=(mass of the swollen sample−mass of the dried sampleafter swelling)/(mass of the dried sample after swelling)

Soluble fraction=(mass of the dry sample before swelling−mass of thedried sample after swelling)/(mass of the dried sample after swelling)

TABLE 2 Mass before Mass Mass dried Soluble swelling swollen Swellingafter swelling fraction Sample [mg] [mg] ratio [mg] [%] 1 81.5 2131 2776 7.2 2 184 3874 21.7 171 7.6 3 151 3610 23.1 150 0.7

5.10. Recycling of a Cross-Linked Polymer Network after Processing ViaInjection Molding/Mechanical Testing/Grinding to Powder

The following example represents a solid formulation, its mechanicalcharacterization, its processing via injection molding, and illustratesthe aptitude of the cross-linked polymer networks described in theinvention to be recycled several times without significant degradationof their mechanical properties.

A DSM Xplore micro 10 cm³ injection molding machine was used to preparedumbbell shape samples (length ca 7 cm). 3 g of the cross-linked polymernetwork NY1 are introduced into the injection molding machine as apowder or as small fragments at RT. The cross-linked polymer network NY1is then injected at 200° C. under 12 bar of pressure into the preheatedmold (180° C.) during a total of 15 to 30 seconds, before cooling downto 45° C. by using a water circuit (ca. 3 minutes).

Samples obtained from the cross-linked polymer network NY1 with the adumbbell shape were then tested in traction using an Instron 5564tensile machine mounted with a 2 kN cell. Specimens were tested inquintuplicate at a fixed crosshead speed of 1.5 mm/min. The samples wereelongated to rupture, cut down to small fragments and re-processed viainjection molding following the procedure described in the previousparagraph. This procedure was repeated 3 times. The Young's modulus wasdetermined as the initial slope of the stress-strain curves.

FIG. 24 represents the average stress at break (ordinate, MPa) ofsamples of the cross-linked polymer network NY1 not recycled (abscissa,0), of samples of the cross-linked polymer network NY1 recycled 1 time(abscissa, 1), of samples of the cross-linked polymer network NY1recycled 2 times (abscissa, 2), of samples of the cross-linked polymernetwork NY1 recycled 3 times (abscissa, 3).

This analysis indicates that the stress at break of the cross-linkedpolymer network NY1 does not decrease significantly after severalrecycling and re-processing cycles.

FIG. 25 represents the average Young's modulus (ordinate, GPa) ofsamples of the cross-linked polymer network NY1 not recycled (abscissa,0), of samples of the cross-linked polymer network NY1 recycled 1 time(abscissa, 1), of samples of the cross-linked polymer network NY1recycled 2 times (abscissa, 2), of samples of the cross-linked polymernetwork NY1 recycled 3 times (abscissa, 3).

This analysis indicates that the Young's modulus of the cross-linkedpolymer network NY1 does not decrease significantly after severalrecycling and re-processing cycles.

5.11. Environmental Stress Cracking on a PSt with Pending DioxaborolaneFunctions (Polymer P2e) and on a Polystyrene Cross-Linked Network (NY2)

The following example represents a solid formulation and illustrates thesuperior solvent resistance and mechanical properties of thecross-linked polymer networks described in the invention as compared tothermoplastic polymers of similar chemical nature.

Environmental stress cracking of polystyrene with pending dioxaborolanefunctions, Polymer P2e, and of cross-linked polystyrene network NY2 wasperformed using a TA Instruments Q800 in three point bending geometry.Rectangular samples prepared by compression molding at 150° C. under apressure of 3 to 5 tons for 5 minutes were used. Their dimensions were:length of 30 mm, width of 15.8 mm, thickness of 1.4 mm. Environmentalconditions were simulated by placing the samples on the two lower tipsof a demounted three point bending set-up in a closed beaker containinga mixture of 300 mL of ethanol/water (9/1). Stress was applied bypositioning a weight of 41 g on the center of the samples for differenttime intervals. The samples were removed, dried on both sides with apaper towel and left at room temperature for 20 more minutes beforetesting their mechanical resistance. To do so, the samples weresubsequently placed in a three point bending set-up and the force wasramped at 3 N/min to a maximum force of 18 N (maximum limit of themachine) at 35° C.

The results are reported in table 3, below.

TABLE 3 Immersion time in a 9/1 Stress at break ethanol/water mixtureunder in three point Sample a weight of 41 g (min) bending (MPa)Polystyrene P2e 0 No rupture Polystyrene P2e 2 26.8 Polystyrene P2e 1023.9 Polystyrene P2e 20 18.0 Polystyrene network NY2 0 No rupturePolystyrene network NY2 2 No rupture Polystyrene network NY2 30 Norupture Polystyrene network NY2 180 No rupture

5.12. Example of a Solid Formulation Using Compound 14 or Additive C1:Network NZ1

The following examples represent a solid formulation and illustrate theformation of cross-linked high-density polyethylene network according tothe invention using the additive C1.

The formation of the cross-linked high-density polyethylene network NZ1was carried out using a DSM Explore batch twin-screw extruder (5 cm3capacity) equipped with co-rotating conical screw profile andrecirculation channel to control the residence time. Dry blends of HDPE,compound 14 or additive C1 (4 wt %) and dicumyl peroxide (0.3 wt %) wereprepared prior to introduction in the extruder. Melt grafting wasperformed under nitrogen atmosphere with a barrel temperature of 200°C., a screw speed of 100 rpm and a residence time of 6 minutes.Extrudates were collected and let to cool down to room temperature. Theresulting cross-linked polymer network is called NZ1.

5.13. Recycling of a Cross-Linked Polymer Network after Processing ViaCompression Molding/Mechanical Testing/Grinding to Powder

The following example represents a solid formulation, its mechanicalcharacterization, its processing via compression molding, andillustrates the aptitude of the cross-linked polymer networks describedin the invention to be recycled several times without significantdegradation of their mechanical properties.

Samples Preparation By Compression Molding

HDPE dumbbell specimen (ISO 527-2 type 5B) were prepared via compressionmolding of the cross-linked high-density polyethylene network NZ1 at200° C. under a pressure of 3 to 5 tons for 5 minutes. Samples weregenerated using a film shape (thickness of 1.5 mm) frame and a punchcutter.

Uniaxial tensile tests were performed at room temperature on thedumbbell-shaped specimens of the cross-linked high-density polyethylenenetwork NZ1 using an Instron 5564 tensile machine mounted with a 2 kNcell. Specimens were tested in quintuplicate at a fixed crosshead speedof 10 mm/min. Engineering stress-strain curves were obtained throughmeasurements of the tensile force F and crosshead displacement Δl bydefining the engineering stress as σ=F/S₀ and the strain as γ=Δl/l₀,where S₀ and l₀ are the initial cross-section and gauge length of thespecimens, respectively. The Young's modulus was determined as theinitial slope of the engineering stress-strain curves. The ultimatetensile strength was determined as the local maximum in engineeringstress at the elastic-plastic transition. In order to test theirrecyclability, the specimens of the cross-linked high-densitypolyethylene network NZ1 were cut down to small fragments after tensiletesting and reshaped via compression molding, following the proceduredescribed in the previous paragraph. This procedure was repeated 3times.

FIG. 26 represents the average tensile strength (ordinate, MPa) ofsamples of the cross-linked polymer network NZ1 not recycled (abscissa,0), of samples of the cross-linked polymer network NZ1 recycled 1 time(abscissa, 1), of samples of the cross-linked polymer network NZ1recycled 2 times (abscissa, 2), of samples of the cross-linked polymernetwork NZ1 recycled 3 times (abscissa, 3).

This analysis indicates that the tensile strength of the cross-linkedpolymer network NZ1 does not decrease significantly after severalrecycling and re-processing cycles.

FIG. 27 represents the average Young's modulus (ordinate, GPa) ofsamples of the cross-linked polymer network NZ1 not recycled (abscissa,0), of samples of the cross-linked polymer network NZ1 recycled 1 time(abscissa, 1), of samples of the cross-linked polymer network NZ1recycled 2 times (abscissa, 2), of samples of the cross-linked polymernetwork NZ1 recycled 3 times (abscissa, 3).

This analysis indicates that the Young's modulus of the cross-linkedpolymer network NZ1 does not decrease significantly after severalrecycling and re-processing cycles.

Example 6. Chemical Uncrosslinking/Recycling of Solid CompositionsContaining Cross-Linked Polymer Networks of the Invention ContainingPending Exchangeable Bonds and Cross-Links Exchangeable by MetathesisReaction of Boronic Esters. Recovery of the Polymers Used to Generatethe Cross-Linked Networks

The following examples illustrate the possibility to chemically recycleand/or to uncrosslinked the cross-linked polymer networks of theinvention.

Samples of the cross-linked polymer network N6 and of the cross-linkedpolymer network NY2 (50-250 mg polymer, n equivalent of boronic esterfunctions, either pending or in the cross-links) were placed inanhydrous tetrahydrofuran and 1,2-propanediol (50-150×n equivalents) wasadded. After one night at room temperature, all samples were completelydissolved. The resulting solution were analyzed by size exclusionchromatography and compared to the linear polymers used to generate thecross-linked polymer networks containing pending exchangeable bonds andcross-links exchangeable by metathesis reaction of boronic esters. Theresults are reported in table 4, below.

GPC results of linear precursors, of cross-linked polymer network N6after chemical uncrosslinking (processed once by injection molding andprocessed and recycled three times by successive injectionmolding/grinding) and of cross-linked polymer network NY2 after chemicaluncrosslinking

TABLE 4 # M_(n) (g/mol) M_(w) (g/mol) Ð Processing Cross-linked polymernetwork N6 Precursor: Polymer 86 000 120 000 1.40 — P2d Cleaved networkN6 75 000 105 000 1.40 1 injection/ molding. Cleaved network N6 76 000108 000 1.42 3 injection/ molding Cross-linked polymer network NY2Parent 11 76 000 130 000 1.71 — Cleaved network 76 000 129 000 1.70 NY2

This examples illustrates the fact that the cross-linked polymernetworks of the invention containing pending exchangeable bonds andcross-links exchangeable by metathesis reaction of boronic esters can bechemically uncrosslinked to recover the polymer with pendingexchangeable boronic ester bonds. This property is of great interest toremove/detach, recover and recycle the cross-linked polymer network ofthe invention.

Example 7. Adhesion Between Cross-Linked Polymer Networks of theInvention Containing Pending Exchangeable Bonds and Cross-LinksExchangeable by Metathesis Reaction of Boronic Esters

The following example illustrates the possibility to stick/glue togethertwo cross-linked polymer networks of the invention containing pendingexchangeable bonds and cross-links exchangeable by metathesis reactionof boronic esters. The polymer constituting the two polymer networks canbe of the same nature or of different nature, as exemplified in thefollowing example between the cross-linked PMMA network N6 and thecross-linked HDPE network NZ1.

Films of the cross-linked PMMA network N6 were compression molded at180° C. for 10 minutes under a pressure of 3 to 5 tons and cut intostrips of 25 mm in length (L), 16 mm in width (w) and 1.5 mm inthickness (h). Films of the cross-linked HDPE network NZ1 werecompression molded at 200° C. for 5 minutes under a pressure of 3 to 5tons and cut into strips of 25 mm in length (L), 16 mm in width (w) and1.5 mm in thickness (h). Lap joints consisting of two single laps wereprepared by placing one strip of cross-linked PMMA network N6 onto twoseparated strips of cross-linked HDPE network NZ1, with both overlaplengths l₀ equal to 1 cm. The lap joints were heated at 190° C. in anoven with a weight of 450 g placed on top of the strip of cross-linkedPMMA network N6 in order to ensure contact in both overlap areas for 10minutes, respectively 20 minutes. The weight was then removed and thelap joints were allowed to cool down to room temperature prior totesting. Lap-shear tests were performed with a speed of 10 mm/min usingan Instron 5564 tensile machine mounted with a 2 kN cell. The distancebetween grips was 27 mm. Three lap joints were prepared and tested foreach contact time.

FIG. 28 shows a schematic representation of the lab joints consisting oftwo single laps obtained by placing one strip of cross-linked PMMAnetwork N6 (dark grey) onto two separated strips of cross-linked HDPEnetwork NZ1 (light grey), with both overlap lengths l₀ equal to 1 cm.

FIG. 29 represents the force normalized by the width (ordinate, kN/m) asa function of displacement (abscissa, mm) during the lap-shear testingof the cross-linked HDPE network NZ1/cross-linked PMMA networkN6/cross-linked HDPE network NZ1 lap joints glued for 10 min (solidline), respectively 20 min (dash line), at 190° C.

This experiment illustrates the possibility to stick/glue together twocross-linked polymer networks of the invention containing pendingexchangeable bonds and cross-links exchangeable by metathesis reactionof boronic esters.

Example 8. Dimensional Stability and Mechanical Property at HighTemperature of Cross-Linked Polymer Networks of the Invention ContainingPending Exchangeable Bonds and Cross-Links Exchangeable by MetathesisReaction of Boronic Esters as Compared to Commercial Thermoplastics Usedto Prepare the Cross-Linked Polymer Network

The following example illustrates the superior dimensional stability andmechanical properties at high temperature of the cross-linked polymernetworks of the invention as compared to linear or branchedthermoplastics of similar chemical nature.

The dimensional stability of a commercial HDPE (purchased from SigmaAldrich, referenced as 428078, melt index 2.2 g/10 min at 190° C. for2.16 kg) and of a crosslinked HDPE network (prepared from thiscommercial HDPE), network NZ1, above their melting temperatures werecompared. A strip (49 mm in length, 16 mm in width and 1.5 mm inthickness) of the commercial HDPE and of the cross-linked polymernetwork NZ1 were subjected to extensional creep by fixing their top partbetween grips and attaching a weight of 258 g (stress of 105.4 kPa) totheir bottom part. Heat was applied to the each strip using two heatguns (one on each side, with the same tip-to-sample distance, ca. 5-5.5cm), and the temperature of the strip was monitored using a thermocouplein contact with the strip’ surface. The melt temperature (˜130° C.) wasattained approximately 10 s after the ignition of the heat guns and thetemperature measured by the thermocouple was kept between 170° C. and200° C. during the rest of the experiment. The strip of commercial HDPEmelted and broke after ca. 20 seconds above 130° C. (ca. 30 secondsoverall), while the strip of cross-linked HDPE network is NZ1 did notbreak even after 10 minutes and only elongated of about 1.5 cm.

The invention allows the preparation of vinylic networks

These vinylic networks can be obtained by copolymerization:

Example 9. Example of Compositions Containing a Cross-Linked PolymerNetwork Containing Pending Exchangeable Bonds and Cross-LinksExchangeable by Metathesis Reaction of Boronic Esters, the Network isObtained by Copolymerization

The following two examples represent compositions containing across-linked polymer network containing pending exchangeable bonds andcross-links exchangeable by metathesis reaction of boronic esters. Inthese two examples, the polymer network is prepared either by radicalcopolymerization of a monomer c and a monomer a in the presence of across-linking agent of formula (Ia), or by radical copolymerization of amonomer c, a monomer a and a monomer b according to the invention.

9.1. Example of Compositions Containing a Cross-Linked Polymer NetworkContaining Pending Exchangeable Bonds and Cross-Links Exchangeable byMetathesis Reaction of Boronic Esters, the Described being Prepared byRadical Copolymerization of a Monomer a and a Monomer c in the Presenceof a Cross-Linking Agent of Formula (Ia) According to the Invention.

The monomer a, or monomer M3 (220 mg, 0.763 mmol), the compound offormula (Ia), or cross-linking agent R1 (37.6 mg, 0.153 mmol), methylmethacrylate, MMA, or monomer c, (1.53 g, 15.27 mmol) and AIBN (2.63 mg,0.016 mmol) are mixed in 0.4 mL of anisole and the reaction mixture isbubbled with nitrogen for 10 minutes at RT. The mixture is then stirredat 65° C. for 17 hours. A cross-linked polymer network according to theinvention is thus obtained.

9.2. Example of Compositions Containing a Cross-Linked Polymer NetworkContaining Pending Exchangeable Bonds and Cross-Links Exchangeable byMetathesis Reaction of Boronic Esters, the Described Network is Obtainedby Radical Copolymerization of a Monomer a, a Monomer b and a Monomer cAccording to the Invention.

The monomer a, or monomer M3 (288 mg, 0.99 mmol), the monomer b, ormonomer M1, (318 mg, 0.99 mmol), methyl methacrylate, MMA, or monomer c,(2.0 g, 19.9 mmol) and AIBN (3.6 mg, 0.022 mmol), are mixed in 0.9 mL ofanisole and the reaction mixture is bubbled with nitrogen for 10minutes. The mixture is then stirred at 65° C. for 24 hours. Across-linked polymer network according to the invention is thusobtained.

REFERENCES

-   1 S. Yu, R. Zhang, Q. Wu, T. Chen, P. Sun, Bio-inspired    high-performance and recyclable cross-linked polymers. Adv. Mater.    25, 4912-4917 (2013)

1. Combinations to cross-link linear or branched polymers, saidcombinations being chosen from among the combinations comprising: A+B;A+C; A+B+C; B+C; A+compound of formula (Ia); or B+compound of formula(Ib1) or (Ib2); A, B and C corresponding to the following formulas:

wherein G₁, G₂, G₃ and G₄ each represent, independently from oneanother, a functional group enabling the covalent binding of themolecules to the polymer chain to be functionalised; Rx, R″x, and Ry,R′y, R″y are hydrocarbon groups; R′v, R′w and R′x, identical ordifferent, each represent a hydrogen atom, a hydrocarbon radical, orform together, as a pair, an aliphatic or aromatic ring; Rv and Rw,respectively R″v and R″w, identical or different, represent a hydrogenatom or a hydrocarbon radical or form an aliphatic or aromatic ringtogether, or with Rx, respectively or with R″x; Ry, R′y, R″y are linkedto the boron through a carbon atom, compounds of formula (Ia) and (Ib)corresponding to the following formulas:

wherein n is a whole number between 1 and 6; i is a whole number between1 and n; k equals 0 or 1; each ki equals 0 or 1; R₁, R′₁, R″₁, R_(3i),R″_(3i), R₅, R″₅, R_(7i), R″_(7i), identically or differently, eachrepresent, independently from one another, a hydrogen atom or ahydrocarbon group; R₆, each R_(8i) identical or different, eachrepresent a hydrocarbon group; {R₁, R′₁, R″₁} can together form, inpairs, an aliphatic or aromatic ring; {R_(3i), R′_(3i), R″_(3i)} cantogether form, in pairs, an aliphatic or aromatic ring; {R₅, R″₅} cantogether form an aliphatic or aromatic ring; {R_(7i), R″_(7i)} cantogether form an aliphatic or aromatic ring; R₂ and R₄, identical ordifferent, each represent a hydrocarbon group; R₂, is linked to theboron atom by a covalent bond through a carbon atom; R₆, each R_(8i) islinked to the boron atom by a covalent bond through a carbon atom. 2.Combinations to cross-link linear or branched polymers according toclaim 1, wherein G₁, G₂, G₃ and G₄ are identical.
 3. Combinations tocross-link linear or branched polymers according to claim 1, wherein G₁,G₂, G₃ and G₄ each represent, independently from one another, afunctional group chosen among a thiol function, a maleimide function, amethacrylic function, an acrylic function, a styrenic function, a maleicester function, an isocyanate function, an electrophilic olefin, anucleophilic function, an alcohol function and an amine function. 4.Combinations to cross-link linear or branched polymers according toclaim 3, wherein G₁, G₂, G₃ and G₄ are chosen among acrylate,acrylamide, maleimide, methacrylate and vinylic sulfones. 5.Combinations to cross-link linear or branched polymers according toclaim 3, wherein the nucleophilic function is chosen among alcohol,thiol, amine and carboxlic acid.
 6. Combinations to cross-link linear orbranched polymers according to claim 1, wherein Rx, R′x and R″x eachrepresent, independently of one another, an aliphatic, aromatic,arylaliphatic or cycloaliphatic radical, said radical containing anheteroatom or not and said radical being substituted or not. 7.Combinations to cross-link linear or branched polymers according toclaim 6, wherein the radical Rx, R′x or R″x is substituted by a halogen,an -Rz, —OH, —NH2, —NHRz, —NRzR′z, —C(O)—H, —C(O)—Rz, —C(O)—OH,—C(O)—NRzR′z, —C(O)—O-Rz, —O—C(O)-Rz, —O—C(O)—O-Rz, —O—C(O)—N(H)-Rz,—N(H)—C(O)—O-Rz, —O-Rz, —SH, —S-Rz, —S—S-Rz, —C(O)—N(H)-Rz,—N(H)—C(O)-Rz group with Rz, R′z, identical or different, representing aC₁-C₅₀ alkyl radical.
 8. Combinations to cross-link linear or branchedpolymers according to claim 7, wherein the radical Rx, R′x or R″xincludes ester, amide, ether, thioether, secondary or tertiary amine,carbonate, urethane, carbamide or anhydride functions.
 9. Combinationsto cross-link linear or branched polymers according to claim 1, whereinRy, R′y and R″y each represent, independently of one another, analiphatic, aromatic, arylaliphatic or cycloaliphatic radical linked tothe boron atom of the dioxaborolane or dioxaborinane ring through acarbon atom, said radical containing an heteroatom or not and saidradical being substituted or not.
 10. Combinations to cross-link linearor branched polymers according to claim 9, wherein the radical Ry, R′yor R″y is substituted by a halogen, an -Rz, —OH, —NH2, —NHRz, —NRzR′z,—C(O)—H, —C(O)—Rz, —C(O)—OH, —C(O)—NRzR′z, —C(O)—O-Rz, —O—C(O)-Rz,—O—C(O)—O-Rz, —O—C(O)—N(H)-Rz, —N(H)—C(O)—O-Rz, —O-Rz, —SH, —S-Rz,—S—S-Rz, —C(O)—N(H)-Rz, —N(H)—C(O)-Rz group with Rz, R′z, identical ordifferent, representing a C₁-C₅₀ alkyl radical.
 11. Combinations tocross-link linear or branched polymers according to claim 10, whereinthe radical Ry, R′y or R″y includes ester, amide, ether, thioether,secondary or tertiary amine, carbonate, urethane, carbamide or anhydridefunctions.
 12. Combinations to cross-link linear or branched polymersaccording to claim 1, wherein n is a whole number between 1 and
 4. 13.Combinations to cross-link linear or branched polymers according toclaim 1, wherein R₂ and R₄ identical or different, represent a ring. 14.Combinations to cross-link linear or branched polymers according toclaim 1, wherein R₂ and R₄ identical or different, are each analiphatic, aromatic, arylaliphatic or cycloaliphatic group whichcontains heteroatoms or not.
 15. Combinations to cross-link linear orbranched polymers according to claim 14, wherein R₂ and R₄, identical ordifferent, each represent a C₁-C₁₂ alkanediyl group, a benzene ring, anaphthalene ring, an arylaliphatic group comprising two benzene ringslinked by a C₁-C₆ alkanediyl group, a pyrimidine ring or a triazinering.
 16. Combinations to cross-link linear or branched polymersaccording to claim 1, wherein R₁, R′₁, R″₁, R_(3i), R′_(3i), R″_(3i),R₅, R″₅, R_(7i), and R″_(7i), identical or different, represent ahydrogen atom or an alkyl, alkenyl, aryl, cycloalkyl, heteroaryl,heteroalkyl or heterocycloalkyl group, and each of these groups issubstituted or not, or R₁, R′₁, R″₁, or R_(3i), R′_(3i), R″_(3i), or R₅,R″₅, or R_(7i), R″_(7i), together form, in pairs, an aliphatic oraromatic ring.
 17. Combinations to cross-link linear or branchedpolymers according to claim 1, wherein said combinations are chosen fromamong the combinations comprising: A+B; A+C; B+C; or A+B+C. 18.Combinations to cross-link linear or branched polymers according toclaim 1, wherein said combinations are chosen from among thecombinations comprising: A+compound of formula (Ia); or B+compound offormula (Ib1) or (Ib2).